Paint shop and method of operating a paint shop

ABSTRACT

In a paint plant which comprises at least one spray-painting device incorporating at least one application unit for painting workpieces and in particular motor vehicle bodies with a fluid paint, in order to enable the fluid paint overspray i.e. the paint particles which are not adhering to the workpieces that are to be painted and which are picked up and carried along in an air flow passing through the application area of the paint shop, to be re-separated from this air flow and also to enable the cleansed air flow to be returned to the application area in an air re-circulating system or else expelled into the environment of the plant, the paint shop comprises a device for separating fluid paint overspray from a stream of crude gas that contains overspray particles wherein this device comprises at least one filter element for separating the overspray from the stream of crude gas.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/163,316 filed Jun. 17, 2011 now U.S. Pat. No. 8,431,180, which is acontinuation application of PCT/EP2009/001305 filed Feb. 24, 2009, whichclaims the benefit of German Patent Application No. DE 10 2008 064043.3, filed Dec. 19, 2008, the specifications of which are incorporatedherein by reference in their entireties and for all purposes.

FIELD OF DISCLOSURE

The present invention relates to a paint shop which comprises at leastone painting device incorporating at least one application unit forpainting workpieces and especially vehicle bodies with a fluid paint,and a device for separating fluid paint overspray from a stream of crudegas containing overspray particles, wherein this device comprises atleast one filter element for separating the overspray from the stream ofcrude gas.

Such a paint shop enables the fluid paint overspray, i.e. the fluidpaint which is not adhering to the workpieces that are to be painted andwhich is picked up and carried along in the form of overspray particlesby an air flow passing through the application area of the paint shop,to be re-separated from this air flow and also enables the cleansed airflow to be returned to the application area in an air re-circulatingsystem or expelled into the environment of the plant.

The term “fluid paint” is used in this description and in theaccompanying Claims—in contrast to the term “powder coating”—todesignate a paint having a fluidic consistency, from liquid to pasty (inthe case of a PVC paint for example). In particular, the term “fluidpaint” encompasses the terms “liquid paint” and “wet paint”.

The overspray particles of which the fluid paint overspray consists maybe solid or liquid particles and in particular, droplets.

SUMMARY OF THE INVENTION

In a special embodiment of the invention, provision is made for thedevice for separating fluid paint overspray from the stream of crude gascontaining overspray particles to comprise at least one filter devicefor separating fluid paint overspray from the stream of crude gascontaining overspray particles which comprises at least one filterelement for separating the overspray from the stream of crude gas and atleast one auxiliary material reservoir for accommodating a filteringmaterial, wherein the filter device comprises at least one inlet openingthrough which the stream of crude gas enters the filter device such thatit is directed into the auxiliary material reservoir.

Hereby, the auxiliary material serves as a barrier layer which isdeposited on the surfaces of the filter element in order to preventthese surfaces from sticking together due to the adhering oversprayparticles. Furthermore, the auxiliary material serves to achieve theeffect that the filter cake in the filter element remains passable to aflowing medium and is not closed.

By periodically cleaning the filter elements of the filter device, themixture of auxiliary material and fluid paint overspray passes from thefilter elements into the auxiliary material reservoir and from there, itcan be e.g. sucked out so as to be fed back to the paint shop forrenewed use as an auxiliary material.

Furthermore, the mixture of auxiliary material and fluid paint overspraypresent in the auxiliary material reservoir may be whirled up by meansof blasts of compressed air from a compressed air lance so that it risesup from the auxiliary material reservoir and is then deposited on thefilter elements.

The fluidic particle-like auxiliary material is also referred to as a“precoat” material or filter aid material.

The described arrangement of the filter device enables auxiliarymaterial to be applied to the at least one filter element in a simpleand efficient manner without the auxiliary material entering theapplication area in which the stream of crude gas absorbs the fluidpaint overspray.

Preferably, provision is made for the inlet opening of the filter deviceto be configured and oriented in such a manner that the stream of crudegas enters the filter device such that it is directed into the auxiliarymaterial reservoir in that it is diverted in an interior space of theauxiliary material reservoir.

Due to the fact that the stream of crude gas is diverted directly intothe auxiliary material reservoir, the effect is achieved that anadequate quantity of auxiliary material is supplied to the stream ofcrude gas and/or that an adequate quantity of auxiliary material whichhas been whirled up by means of a fluidising device is carried from theauxiliary material reservoir to the at least one filter element by thestream of crude gas.

The stream of crude gas enters a filter device through the inletopening, said filter device being otherwise closed with respect to theflow path of the stream of crude gas located prior to the inlet openingand also with respect to the application area of the paint shop. It isthereby ensured furthermore, that no auxiliary material from theauxiliary material reservoir will get into the flow path of the streamof crude gas located prior to the inlet opening or into the applicationarea since, for this to happen, this auxiliary material would have tomove against the direction of flow of the stream of crude gas throughthe inlet opening.

By virtue of using such a filter device, one may dispense with anadditional nozzle arrangement for injecting auxiliary material into thestream of crude gas.

Furthermore, it is not necessary when using such a filter device totemporarily close parts of the flow path of the stream of crude gas fromthe application area to the filter device during the process ofintroducing auxiliary material into the stream of crude gas.

Preferably, the auxiliary material is introduced into the stream ofcrude gas exclusively within the filter device, after the stream ofcrude gas has passed the inlet opening of the filter device.

In order to enable the direction of flow of the stream of crude gas tobe orientated in as precise a manner as possible, provision ispreferably made for the inlet opening to be in the form of an inletchannel extending in the direction of flow of the stream of crude gas.

In order to increase the maximum rate of flow of the stream of crude gasin the inlet channel, provision may be made for the inlet channel tohave a through-flow cross section which narrows in the direction of flowof the stream of crude gas up to a narrow section.

In order to reduce the rate of flow of the stream of crude gas after itspassage through the narrow section at which the stream of crude gasexhibits its maximum rate of flow and thereby prevent the stream ofcrude gas from striking the auxiliary material in the auxiliary materialreservoir at too high a rate of flow, provision may be made for theinlet channel to have a through-flow cross section which expands in thedirection of flow of the stream of crude gas onwardly from a narrowsection.

In a preferred embodiment of the invention, the inlet opening is boundeddownwardly by a lower guidance surface.

For the purposes of guiding the stream of crude gas into the auxiliarymaterial reservoir in the desired manner, it is expedient if the lowerguidance surface is inclined to the horizontal at least in sectionsthereof, namely in particular, such that that the lower guidance surfaceis inclined downwardly—as seen in the direction of flow of the stream ofcrude gas.

It has proved to be particularly expedient, if the lower guidancesurface is inclined to the horizontal at least in sections thereof at anangle of at least approximately 30°, preferably at an angle of at leastapproximately 40°.

Furthermore, it has proved to be expedient for the lower guidancesurface to be inclined to the horizontal at least in sections thereof atan angle of at most approximately 75°, preferably of at mostapproximately 65°.

In order to prevent the stream of crude gas breaking-away from the lowerguidance surface and to ensure a directed flow into the auxiliarymaterial reservoir, it is of advantage if the lower guidance surface hasan upper section and a lower section which follows on the upper sectionin the direction of flow of the stream of crude gas, wherein the lowersection is inclined to the horizontal to a greater extent than the uppersection.

Furthermore, it is expedient for the guidance of the stream of crudegas, if the inlet opening is bounded upwardly by an upper guidancesurface.

Preferably, the upper guidance surface is also inclined to thehorizontal at least in sections thereof, namely in particular, in such amanner that the upper guidance surface is inclined downwardly—as seen inthe direction of flow of the stream of crude gas.

Hereby, it has proved to be expedient for the upper guidance surface tobe inclined to the horizontal at least in sections thereof at an angleof at least approximately 30°, preferably at an angle of at leastapproximately 40°.

Moreover, it has proved to be expedient for the upper guidance surfaceto be inclined to the horizontal at least in sections thereof at anangle of at most approximately 75°, preferably at an angle of at mostapproximately 65°.

The average rate of flow of the stream of crude gas when passing thenarrowest part of the inlet opening should be sufficiently high as toprevent auxiliary material or fluid paint overspray that has beencleaned off the at least one filter element from leaking out through theinlet opening.

Preferably, the average rate of flow of the stream of crude gas whenpassing the narrowest part of the inlet opening amounts to at leastapproximately 2 m/s, and in particular, to at least approximately 3 m/s.

Furthermore, it has proved to be expedient for the average rate of flowof the stream of crude gas when passing the narrowest part of the inletopening to amount to at most approximately 8 m/s, preferably to at mostapproximately 5 m/s.

In order to achieve a well oriented stream of crude gas into theauxiliary material reservoir, the inlet opening is preferably configuredin such a way that the stream of crude gas does not break-away in theregion of the inlet opening.

In order to achieve the effect that the stream of crude gas loaded withoverspray comes into contact with as few components of the filter deviceupon which the overspray could settle as possible before reaching the atleast one filter element, it is of advantage if the auxiliary materialreservoir is constructed and arranged relative to the inlet opening insuch a manner that the stream of crude gas emerging from the inletopening is diverted in the auxiliary material reservoir towards the atleast one filter element.

In order to achieve the effect that as little auxiliary material aspossible reaches the region of the inlet opening of the filter device,it is expedient for the filter device to comprise at least onerestraining element which keeps the auxiliary material from theauxiliary material reservoir away from the inlet opening.

Such a restraining element is particularly effective, if it projectsinto an interior space of the filter device and/or into an interiorspace of the auxiliary material reservoir.

In a preferred embodiment of the invention, provision is made for therestraining element, which may be in the form of a restraining metalplate for example, to form a lower boundary of the inlet opening.

In this case in particular, provision may be made for the restrainingelement to comprise a section of a guidance surface for the stream ofcrude gas which is inclined to the horizontal to a greater extent than afurther section of the guidance surface that is located before thesection of the guidance surface arranged on the restraining element inthe direction of flow of the stream of crude gas. The stream of crudegas is thereby effectively prevented from breaking-away from theguidance surface.

Furthermore, it is of advantage for the filter device to comprise atleast one filter shielding element which is constructed and arranged insuch a manner that it prevents the crude gas entering the filter devicefrom the inlet opening from flowing directly to the at least one filterelement. The effect is thereby achieved that insofar as possible theentire stream of crude gas entering the filter device will first passdirectly into the auxiliary material reservoir and only then, when it isloaded with auxiliary material, does it reach the at least one filterelement.

In particular, such a filter shielding element may be in the form of ascreening plate.

In order to prevent insofar as possible material (auxiliary material andfluid paint overspray) that has been cleaned off the at least one filterelement from reaching the region of the inlet opening of the filterdevice, it is of advantage for the filter device to comprise at leastone deflector element which keeps material cleaned off the at least onefilter element away from the inlet opening for the crude gas.

Preferably, the at least one deflector element diverts the materialcleaned off the at least one filter element into the auxiliary materialreservoir.

In particular, such a deflector element may be in the form of adeflector plate.

In order to prevent auxiliary material and/or overspray from beingdeposited in the vicinity of the inlet opening, it is of advantage forthe filter device to comprise at least one covering element which coversa corner area of the inlet opening so that auxiliary material and/oroverspray are kept away from the corner area of the inlet opening.

In particular furthermore, such a covering element may have asubstantially triangular covering surface.

In particular, such a covering element may be in the form of a coverplate.

As an alternative or in addition to the provision of such a coveringelement, provision may be made for the inlet opening to have a cornersurface in at least one corner area which is oriented at an angle to thevertical and at an angle to the horizontal so that auxiliary materialand/or overspray slides downwardly at the corner surface due to theinclination of the corner surface.

In particular, such a corner surface may be provided on a coveringelement that is provided in the corner area of the inlet opening.

In order to increase the amount of auxiliary material that is absorbedby the stream of crude gas whilst flowing through the auxiliary materialreservoir, the filter device may comprise at least one fluidising devicefor whirling up the auxiliary material that is present in the auxiliarymaterial reservoir.

The filter device described is suitable, in particular, for use in adevice for separating fluid paint overspray from a stream of crude gascontaining overspray particles which comprises at least one such filterdevice and a flow chamber through which the stream of crude gas flowsfrom an application area of a paint shop to the inlet opening of the atleast one filter device.

Preferably thereby, the through-flow cross section of the flow chamberfor the stream of crude gas decreases along the direction of flow of thestream of crude gas up to the at least one inlet opening of the at leastone filter device. Thereby, the rate of flow of the stream of crude gasincreases when flowing through the flow chamber up to the at least oneinlet opening of the at least one filter device, this thus preventingthe auxiliary material and/or overspray from the filter device reachingthe application area of the paint shop against the direction of flow ofthe stream of crude gas.

In particular, provision may be made for the flow chamber to be boundedby at least one substantially horizontal boundary wall by means of whichthe through-flow cross section of the flow chamber for the stream ofcrude gas decreases in step-like manner.

Furthermore, it is of advantage for the device to comprise at least oneflow guide plate which is arranged above at least one filter device andis inclined to the horizontal at an angle of at most approximately 10°and preferably at an angle of at most approximately 3° in such a waythat any liquid reaching the flow guide plate does not get into the flowpath of the stream of crude gas. This, for example, thereby preventsfire-extinguishing water or fluid paint escaping from a burst hose inthe application area from getting into the flow path of the stream ofcrude gas and from there, into the filter device.

If the device comprises at least one gangway that is accessible to anoperator, then the upper surface thereof is preferably inclined to thehorizontal at least in sections thereof at an angle of at mostapproximately 10°, and preferably at an angle of at most approximately3°, in such a way that liquid falling onto the accessible gangway doesnot get into the flow path of the stream of crude gas. This, forexample, also serves the purpose of keeping fire-extinguishing water orfluid paint escaping from a burst hose within the application area outof the flow path of the stream of crude gas through the flow chamber.

The device described for separating fluid paint overspray is suitable,in particular, for use in a plant for painting objects and in particularpainting vehicle bodies which comprises at least one application areafor applying fluid paint to objects that are to be painted and at leastone such device for separating fluid paint overspray.

It has proved to be expedient hereby, if the vertical spacing of theapplication area from the inlet opening of the filter device amounts toat least approximately 1.0 m, preferably to at least approximately 1.5m.

The present invention can offer the advantage that as little oversprayas possible will remain stuck to the walls of the flow chamber or to thewalls of the filter device on its way to the at least one filterelement.

The at least one filter element is preferably accommodated in a box thatis closed insofar as possible so that auxiliary material or overspraycleaned off the filter element will not reach the application areawithout the need for parts of the flow path of the stream of crude gashaving to be occasionally blocked for this purpose.

The air flow within the filter device may be established in such a waythat the distribution of the auxiliary material on the filter element oron the filter elements is effected in as homogeneous a manner aspossible.

The capacity of the filter device described may be matched to the amountof crude gas passing through the application area.

The filter device described is suitable, in particular, for use in dryfluid-paint-overspray precipitations systems for paint booths in theautomobile industry or in more general industrial paint shop areas.

The filter device described enables auxiliary material to be introducedinto the stream of crude gas and cleaning of the filter elements to beeffected during the ongoing painting processes.

The device for separating fluid paint overspray from the stream of crudegas containing overspray particles preferably comprises at least onefilter device for separating fluid paint overspray from the stream ofcrude gas containing overspray particles, wherein the filter devicecomprises at least one filter element for separating the overspray fromthe stream of crude gas and at least one auxiliary material reservoirfor accommodating an auxiliary material. This auxiliary material issupplied to the stream of crude gas that is loaded with fluid paintoverspray before the stream of crude gas has passed at least one filterelement for separating the overspray from the stream of crude gas. Theauxiliary material reservoir is preferably provided with at least onelevel sensor for the purposes of determining the level of the auxiliarymaterial in the auxiliary material reservoir.

This construction of the auxiliary material reservoir enables thecurrent operational state of the auxiliary material reservoir to bemonitored in a simple manner in order to be able to specificallycontrol, in particular, the process of emptying-out a mixture ofauxiliary material and fluid paint overspray from the auxiliary materialreservoir.

In this case, the proportion of the fluid paint overspray in the mixtureof auxiliary material and fluid paint overspray that is present in theauxiliary material reservoir is always increasing in the course ofoperation of the auxiliary material reservoir, this being somethingwhich leads to a decrease in the density of the mixture. Consequently,the volume of the barrier layer which has built up on the at least onefilter element becomes ever greater. The level of the material in theauxiliary material reservoir immediately before the filter element issubjected to a cleaning process therefore continues to decrease.Consequently, the proportion of the fluid paint overspray in the mixturepresent in the auxiliary material reservoir can be assessed from theactual level of the auxiliary material in the auxiliary materialreservoir before the at least one filter element is subjected to acleaning process.

Contrariwise, as the operational period gets longer, the level of thematerial present in the auxiliary material reservoir continues toincrease immediately after the at least one filter element is subjectedto a cleaning process since, due to the cleaning process, the entireamount of material including the separated fluid paint overspray thatwas deposited on the filter element has reached the auxiliary materialreservoir and a new barrier layer has still not built up on the filterelement immediately after a cleaning process. Consequently, theproportion of the fluid paint overspray in the mixture present in theauxiliary material reservoir can also be assessed from the level of thematerial in the auxiliary material reservoir immediately after acleaning process.

Thus, the operational state of the auxiliary material reservoir and thecondition of the material present therein can be reliably monitored, andthis can be done for each auxiliary material reservoir individually, bymeans of a level sensor for the determination of the level of theauxiliary material in the auxiliary material reservoir.

In order to enable the level in the auxiliary material reservoir to bedetermined as precisely as possible, the level sensor is preferably ableto produce a signal which corresponds to a value from a multiplicity ofdiscrete height levels or from a continuum of height levels.

In a preferred embodiment of the invention, provision is made for thelevel sensor to be in the form of an analogue sensor.

In particular, the level sensor may be in the form of a capacitivesensor.

In order that the result of the measurement made by the level sensorwill be impaired to the least possible extent by edge effects, it is ofadvantage if the level sensor is arranged in an interior space of theauxiliary material reservoir in such a way that it is spaced from thewalls of the auxiliary material reservoir.

It has proved to be particularly expedient for the level sensor tocomprise a substantially rod-shaped sensor element.

The longitudinal direction of the level sensor, thus in particular, thelongitudinal direction of the rod-shaped sensor element is preferablyoriented substantially vertically in order to obtain as large aresolution as possible in regard to the different measurable heightlevels.

Preferably, the longitudinal direction of the level sensor, thus inparticular, the longitudinal direction of the rod-shaped sensor elementis oriented substantially perpendicularly to a base of the auxiliarymaterial reservoir.

In order to enable the material present in the auxiliary materialreservoir to be thoroughly mixed and its surface smoothed as well as toenable material bridges caused by an undermining process to be brokenup, it is of advantage for the auxiliary material reservoir to beprovided with a means for mixing the material that is present in theauxiliary material reservoir.

Such a mixing device may, for example, be in the form of a fluid base ofthe auxiliary material reservoir through which a gaseous medium and inparticular compressed air may pass in order to fluidise the materialpresent in the interior space of the auxiliary material reservoir andthus locally equalize different height levels of the material within theauxiliary material reservoir.

As an alternative or in addition thereto, provision may also be made forthe auxiliary material reservoir to be provided with an agitator formixing the material and homogenizing the contents.

Such an agitator may comprise a shaft provided with paddles.

The shaft may be oriented substantially horizontally or substantiallyvertically.

The paddles may be arranged on the shaft such as to be angularly spacedfrom each other and/or mutually displaced in the axial direction of theshaft.

The shaft may be set into rotary motion by an electric motor forexample.

As an alternative or in addition thereto, provision may also be made forthe shaft to be set into rotary motion pneumatically, and in particular,by means of a turbine that is subjected to compressed air. A pneumaticdrive offers the advantage that sparking is avoided and adequateprotection from explosion is thereby ensured.

In order to prevent the base of the auxiliary material reservoir, and inparticular a fluid base, from being damaged by larger falling objects,it is expedient for the auxiliary material reservoir to comprise atleast one retaining device which prevents the objects from reaching thebase of the auxiliary material reservoir.

Such a retaining device may comprise, in particular, a retaining gridwhich is arranged above the base of the auxiliary material reservoir andincorporates passage openings for allowing auxiliary material andoverspray to pass through the retaining grid.

In order to make it possible to gain entry to the interior space of theauxiliary material reservoir for maintenance purposes, provision may bemade for the auxiliary material reservoir to have an entrance opening ina side wall thereof and for said entrance to be closable by means of aclosure element.

In particular, provision may be made for the interior space of theauxiliary material reservoir to be accessible to an operator by passingthrough the entrance opening. Hereby, the level sensor may be helddirectly or indirectly on the closure element for the entrance opening,for example on an inspection door.

In order to whirl up the auxiliary material and thus introduce it intothe stream of crude gas being passed through the auxiliary materialreservoir and/or in order to obtain homogenisation of the mixtureconsisting of auxiliary material and the overspray bound thereto whichis present in the auxiliary material reservoir, the auxiliary materialreservoir may be provided with a fluidising device for whirling up theauxiliary material present in the auxiliary material reservoir.

In this case, it is particularly expedient for maintenance and repairpurposes, if the level sensor is connected to the fluidising device soas to form a common manipulable unit.

In particular, provision may be made for the level sensor and thefluidising device to be held together on the closure element for theentrance opening in the side wall of the auxiliary material reservoir sothat the level sensor and the fluidising device are removable from theinterior space of the auxiliary material reservoir by removing theclosure element from the entrance opening.

The fluidising device preferably comprises at least one outlet nozzlefor a gaseous medium which is at an enhanced pressure.

The outlet nozzle may be arranged statically or in rotatable manner on amounting plate of the fluidising device.

In both cases, provision may be made for the orientation of the outletnozzle relative to the side walls of the auxiliary material reservoir tobe adjustable.

In the case of the gaseous medium of enhanced pressure, this may, forexample, be compressed air at an absolute pressure of at leastapproximately 2 bar.

Preferably, the fluidising device comprises at least two outlet nozzles.A larger number of outlet nozzles such as four outlet nozzles forexample, is also conceivable.

The outlet nozzle is preferably arranged approximately centrally in theauxiliary material reservoir. The spacing to the upper surface of thematerial in the auxiliary material reservoir should amount to at leastapproximately 15 cm.

Preferably, at least one outlet nozzle of the fluidising device is inthe form of a conical jet.

In one preferred embodiment of the invention, the gaseous mediumemerging from the outlet nozzle or from the outlet nozzles forms amedian cone which stretches over substantially the entire base surfaceof the auxiliary material reservoir so as to thereby obtain improvedutilization of the material contained therein.

The auxiliary material reservoir described is suitable in particular foruse in a filter device for separating fluid paint overspray from a crudegas containing overspray particles which comprises at least one filterelement for separating the overspray from the stream of crude gas and atleast one such auxiliary material reservoir.

Hereby, the auxiliary material reservoir is preferably arranged below atleast one filter element of the filter device in such a way that, whencleaning the filter elements, the material (a mixture of auxiliarymaterial and fluid paint overspray) dropping down therefrom enters theauxiliary material reservoir.

Furthermore, provision is preferably made for the auxiliary materialreservoir to be located in the flow path of the stream of crude gasflowing through the filter device from an inlet opening to the at leastone filter element.

It is particularly expedient, if the stream of crude gas enters thefilter device through the inlet opening of the filter device such thatit is directed directly into the auxiliary material reservoir and isdeflected in the auxiliary material reservoir in such a way that it thenflows to the at least one filter element.

The auxiliary material reservoir preferably contains a mixtureconsisting of auxiliary material and fluid paint overspray bound theretowhich reaches the auxiliary material reservoir due to the process ofcleaning the at least one filter element.

The filter device described is particularly suitable for use in a devicefor separating fluid paint overspray from a stream of crude gascontaining overspray particles which comprises at least one such filterdevice and a flow chamber through which the stream of crude gas flowsfrom an application area of a paint shop to an inlet opening of the atleast one filter device.

Such a device for separating fluid paint overspray is particularlysuitable for use in a plant for painting objects, and in particularvehicle bodies, which comprises at least one application area forapplying fluid paint to the objects that are to be painted and at leastone such a device for separating fluid paint overspray.

Furthermore, provision may be made for the paint shop to comprise adevice for introducing auxiliary material into the flow path of a streamof crude gas loaded with fluid paint overspray before the stream ofcrude gas has passed at least one filter element for separating theoverspray from the stream of crude gas, wherein the device forintroducing the auxiliary material comprises the following:

-   -   a detecting device for determining whether there is an adequate        flow of crude gas through the at least one filter element; and    -   a blocking device for blocking the introduction of auxiliary        material into the flow path of the stream of crude gas if the        detecting device determines the lack of an adequate flow of        crude gas.

Thereby, it is possible to reliably prevent the introduction ofauxiliary material into the application area of a paint shop even whenthe system is not operating correctly.

Hereby, an adequate flow of crude gas is to be understood as being astream of crude gas which is such that a predetermined (e.g. empiricallydetermined) minimum quantity of crude gas passes the at least one filterelement for separating the overspray per unit of time.

If no such adequate flow of crude gas through the at least one filterelement is present, then the danger exists that auxiliary materialintroduced into the flow path of the stream of crude gas enters into theapplication area of the paint shop against the normal direction of flowof the stream of crude gas.

Due to the described block on the introduction of auxiliary materialinto the flow path of the stream of crude gas in the absence of anadequate flow of crude gas, the introduction of auxiliary material intothe application area of the paint shop is reliably prevented even in thecase of such an operational malfunction.

Hereby in particular, the device may comprise a control device whichserves as a detecting device for determining whether an adequate flow ofcrude gas is present, and/or as a blocking device for blocking theintroduction of auxiliary material into the flow path of the stream ofcrude gas.

The device for introducing auxiliary material into the flow path of thestream of crude gas preferably comprises at least one fluidising devicefor whirling up the auxiliary material present in an auxiliary materialreservoir, wherein the functioning of the fluidising device is blockablein the absence of an adequate flow of crude gas.

Furthermore, the device for introducing auxiliary material into thestream of crude gas may comprise a cleaning device for cleansingauxiliary material off at least one filter element, wherein thefunctioning of the cleaning device is blockable in the absence of anadequate flow of crude gas.

In particular, provision may be made for the device for introducingauxiliary material into the flow path of the stream of crude gas tocomprise pressure sensors for measuring a decrease of pressure in atleast one filter element.

Furthermore, provision may be made for the device for introducingauxiliary material into the flow path of the stream of crude gas tocomprise at least one device for monitoring the operational state of afan that is arranged downstream of the at least one filter element.

Hereby, the device may, for example, comprise a current monitoringinstrument for monitoring the operational state of the fan.

As an alternative or in addition thereto, the device may comprise afrequency converter for monitoring the operational state of the fan.

As an alternative or in addition thereto, the device may also comprise adifferential pressure gauge for the measurement of the decrease ofpressure at the fan.

Furthermore, provision may be made for the device for introducingauxiliary material into the flow path of the stream of crude gas tocomprise at least one volumetric flow meter.

In particular, provision may be made for at least one volumetric flowmeter to be arranged downstream of the at least one filter element.

Such a device for introducing auxiliary material into the flow path of astream of crude gas loaded with fluid paint overspray is suitable inparticular for use in a device for separating fluid paint overspray froma stream of crude gas containing overspray particles, which comprises atleast one filter element for separating the overspray from the stream ofcrude gas and at least one such a device for introducing auxiliarymaterial into the flow path of the stream of crude gas loaded with fluidpaint overspray.

Such a device for separating fluid paint overspray is particularlysuitable for use in a plant for painting objects, and in particularvehicle bodies, which comprises at least one application area forapplying fluid paint to the objects that are to be painted and at leastone such a device for separating fluid paint overspray.

Furthermore, provision may be made for the device for separating fluidpaint overspray from the stream of crude gas containing oversprayparticles to comprise at least one unit, wherein the unit comprises thefollowing:

-   -   a filter element accommodating chamber for accommodating at        least one filter element for separating the overspray from the        stream of crude gas;    -   at least one auxiliary material reservoir for accommodating an        auxiliary material which is supplied to the stream of crude gas        before the stream of crude gas passes the at least one filter        element;    -   at least one partition wall for separating the filter element        accommodating chamber from a flow chamber of the device for        separating fluid paint overspray through which the stream of        crude gas flows before entering the unit; and    -   at least one inlet opening through which the stream of crude gas        from the flow chamber enters the unit.

Due to the use of one or preferably a plurality of units of this kind,it becomes possible to assemble a device for separating fluid paintoverspray from a stream of crude gas containing overspray particles in aparticularly simple and rapid manner.

By using one or preferably a plurality of units of this kind which arelined up in one or in a plurality of rows in a longitudinal direction ofthe device for separating fluid paint overspray, a device for theseparation of fluid paint overspray having any desired crude gascleaning capacity is created in a simple and rapid manner.

Due to this modular manner of construction, such a device for separatingfluid paint overspray that is built up in modular manner is expandableas desired even after it has first been assembled by adding furthermodules or units when so required.

Such a unit will also be referred to hereinafter as a module, a filtermodule or a filter device.

Hereby, the flow properties of the stream of crude gas in the filterelement accommodating chamber of each unit remain unaffected by theaddition of further units for the purposes of expanding the capacitythereof. The reason for this is that these flow properties are basicallydetermined by the dimensioning of the inlet opening through which thestream of crude gas from the flow chamber enters the unit, and also dueto the fact that each unit is separated by its own partition wall fromthe flow chamber through which the stream of crude gas flows before itsentry into the unit.

The partition wall of the unit may comprise a wall that is set at anangle to the horizontal or a wall that extends substantially vertically.

The inlet opening of the unit may be bounded in the upward direction bya lower edge of the partition wall, and in particular a wall of thepartition wall that is set at an angle to the horizontal or a wall thatextends substantially vertically.

Each of the units thus represents a self-sufficient filter device forseparating fluid paint overspray from a stream of crude gas containingoverspray particles which is usable either individually or together withother units.

In a preferred embodiment of the invention, provision is made for theinlet opening of the unit to be bounded downwardly by a lower guidancesurface.

For the desired guidance of the stream of crude gas into the interiorspace of the unit and in particular into the auxiliary materialreservoir, it is expedient if the lower guidance surface is inclined tothe horizontal at least in sections thereof, namely in particular, insuch a way that the lower guidance surface is inclined downwardly—asseen in the direction of flow of the stream of crude gas.

It has proven to be particularly expedient, if the lower guidancesurface is inclined to the horizontal at least in sections thereof at anangle of at least approximately 30°, preferably at an angle of at leastapproximately 40°.

Furthermore, it has proved to be expedient for the lower guidancesurface to be at least partly in the form of a guidance element whichprojects to one side over a support structure of the unit.

In particular, such a guidance element may be in the form of an intakeslope.

In a preferred embodiment of the unit described, provision is made forthe unit to comprise at least one filter element which is arranged inthe filter element accommodating chamber.

In order to be able to connect the units to one another or to partitionwalls that are respectively arranged between two neighbouring modules ina simple manner, it is expedient for the unit to comprise at least oneconnecting element for connecting the unit to a neighbouring furtherunit or to a neighbouring partition wall.

In particular, such a connecting element may form a part of a supportstructure of the unit.

For example, provision may be made for the connecting element to be inthe form of a substantially vertically running support.

Furthermore, the connecting element may have a contact surface forabutment on a contact surface of a neighbouring unit or a neighbouringpartition wall.

In order in particular to produce such a flat contact surface and toprovide adequate mechanical stability for the arrangement, it isexpedient if the connecting element has a substantially U-shaped crosssection at least in sections thereof.

In order to be able to extract individual units in a simple manner froma row of mutually connected units when this becomes necessary such asfor repair and/or maintenance purposes for example, it is of advantageif the connecting element is connectable in releasable manner to aneighbouring unit or to a neighbouring partition wall.

In particular, provision may be made for the connecting element to beconfigured such as to be bolted to a neighbouring unit or to aneighbouring partition wall.

By bolting the connecting elements to one another, the static loadsustainable by the connecting elements is increased.

In a preferred embodiment of the invention, provision is made for theunit to comprise a support structure which carries at least one of theother elements of the unit, and preferably all the other elements of theunit.

The unit described is preferably arranged to be pre-assembled so thatafter the pre-assembly process, it may be handled and transported as awhole in a pre-assembled state.

The unit described is suitable, in particular, for use in a device forseparating fluid paint overspray from a stream of crude gas containingoverspray particles which comprises at least one such a unit and a flowchamber through which the stream of crude gas flows before the entrythereof into the at least one unit.

In a preferred embodiment of such a device, provision is made for thedevice to comprise at least two units which succeed one another in alongitudinal direction of the device.

Hereby in particular, provision may be made for at least two units to bearranged directly next to each other.

Thereby, the two units may be connected to one another in releasablemanner.

As an alternative thereto, provision may be made for the device tocomprise at least one partition wall by means of which the filterelement accommodating chambers of at least two of the units that succeedone another in a longitudinal direction of the device are separated fromeach other. Due to such a separation of the filter element accommodatingchambers of mutually neighbouring units, longitudinal currents betweenthe filter element accommodating chambers of the units and thus mutualinterference with the flow properties in the units are prevented. Adefined zoned separation of the stream of crude gas through the units isthereby obtained, this thereby resulting in a well-defined setting forthe stream of crude gas within the individual units.

Furthermore, provision may also be made for the device to comprise atleast one partition wall by means of which successive sections of theflow chamber are separated from each other in a longitudinal directionof the device.

Hereby, the partition walls which separate the successive sections ofthe flow chamber from each other in a longitudinal direction of thedevice may be identical to the partition walls which separate the filterelement accommodating chambers of the units that succeed one another inthe longitudinal direction of the device.

Furthermore, in a preferred embodiment of such a device, provision ismade for the device for separating fluid paint overspray to comprise atleast two units which are spaced from each other in a transversedirection of the device.

Hereby, by changing the spacing between the units that are spaced fromeach other in the transverse direction of the device, the overallassemblage of units can be adapted to the width of the flow chamber ofthe device without this entailing any change to the units themselves.

Preferably in this case, the at least two units are arranged in such away that their respective inlet openings face each other.

The region of the flow chamber remaining between the two units havingmutually facing inlet openings forms a narrowed section of the flowchamber in which the rate of flow of the stream of crude gas flowing tothe inlet openings of the units is higher than it is in a section of theflow chamber located above the units. In this way, there is produced arising speed profile in the stream of crude gas, this offering theadvantage that auxiliary material and overspray are more easily keptaway from the inlet openings and held back in the units.

In a preferred embodiment of the invention, provision is made for agangway that is accessible to an operator to be arranged between atleast two of the units which are spaced from each other in a transversedirection of the device.

By means of a variation in the width of the accessible gangway, theoverall assemblage consisting of the units and the accessible gangwayarranged therebetween can be adapted to any desired width of the flowchamber of the device for the separation of fluid paint overspray.

In addition, the height of the overall assemblage of units can be easilyadapted to any desired height of the flow chamber of the device for theseparation of fluid paint overspray by merely altering the length of thesupports of the support structure for the units, or, for example, byadding extension pieces to these supports.

The described device for separating fluid paint overspray isparticularly suitable, for use in a plant for painting objects, and inparticular vehicle bodies, which comprises at least one application areafor applying fluid paint to the objects that are to be painted and atleast one such a device for separating fluid paint overspray.

Preferably thereby, the flow chamber of the device for separating fluidpaint overspray is arranged at least partly underneath the applicationarea.

It is particularly expedient, if the entire device for separating fluidpaint overspray including the flow chamber and the units is arrangedwithin the vertical projection of the application area of the paintshop.

Furthermore, provision may be made for the device for separating fluidpaint overspray from the stream of crude gas containing oversprayparticles to comprise at least two filter devices each of whichincorporates an inlet opening through which a partial stream of crudegas enters the filter device concerned and at least one filter elementfor separating the overspray from the partial stream of crude gas,

wherein the device comprises at least one reservoir for accommodating amaterial cleaned off the filter elements of a plurality of filterdevices and a mixing device for mechanically mixing the materialcleansed from a plurality of filter devices.

By virtue of such an embodiment of the device for separating fluid paintoverspray from the stream of crude gas containing overspray particles,it is possible to maintain the fluidity of the mixture of auxiliarymaterial and of the fluid paint overspray cleaned off the filterelements in the auxiliary material reservoirs in a simple and efficientmanner.

The flow properties of the mixture of auxiliary material and fluid paintoverspray are critical to the correct functioning of such a device forseparating fluid paint overspray. If the flow properties are no longersatisfactory, then material exchange no longer takes place in theauxiliary material reservoirs. The material in the auxiliary materialreservoirs can no longer flow to the suction opening, and thestate-of-filling of the tanks remains above the value which wouldterminate the suction process. In this case, the painting process mustbe interrupted and the material in the auxiliary material reservoirsmust be decompacted manually in such a way that it becomes flowableagain and can thus be sucked out.

Even if the auxiliary material reservoirs are provided with fluid basesin the form of plates of sintered plastic in order to allow the materialcontained in the auxiliary material reservoirs to be fluidised bysupplying compressed air thereto, an adequate decompacting process forre-establishing the desired flow properties of the material cannot beensured thereby. Namely, the adherence properties of the particles inthe mixture consisting of auxiliary material and fluid paint oversprayare substantially stronger than the flow forces produced by thecompressed air so that the layer of the material as a whole willincrease or else channels will form in the material through which thecompressed air will flow upwardly. Additionally, the process offluidising the material is made more difficult due to the large spreadin the distribution of particle sizes of the auxiliary material (in arange of from approximately 2 μm to approximately 100 μm).

For the purposes of fluidising a batch of particles having a diameter of2 μm to a porosity of approximately 0.85, a rate of flow of 0.00016 m/sis enough. For the purposes of fluidising a batch of particles having adiameter of 100 μm, one needs a rate of flow of 0.35 m/s, i.e. a rate offlow that is approximately 2,000 times higher than is the case forparticles having a diameter of 2 μm. Consequently, even if the flowforces should outweigh the forces of adhesion, uniform fluidisationconditions cannot be obtained simply by feeding in compressed air.Rather, a sort of classifying process occurs whereby the fine componentsare carried away whilst the coarse components remain immovably on thebase of the auxiliary material reservoirs. This classifying effect alsoarises if the auxiliary material is whirled up by compressed air blastsby means of fluidising devices located above the auxiliary materialreservoirs.

The concept underlying the solution to this problem described above isthat material cleansed from a plurality of filter devices through eachof which there is a partial stream of crude gas should be collected inone and the same reservoir and mechanically mixed within the reservoirby means of a mixing device in order to mechanically destroy theadhesion between the particles of the cleansed material, to prevent“growth” of the reservoir with the cleansed material and to obtain agreatest possible degree of homogeneity of the material in the reservoirby the process of mixing material cleansed from different filterdevices.

A more secure process is thereby obtained, and the material in thereservoir can be concentrated up to higher level of concentration of thefluid paint overspray contained therein without endangering the fluidityof the mixture of auxiliary material and fluid paint overspray.

If, however, each filter device has its own auxiliary material reservoirassociated thereto, then a very large number of such auxiliary materialreservoirs have to be provided and have to be constantly and preciselymonitored in regard to the composition of the material therein. Due tothe different loading of the different filter devices with fluid paintoverspray which is dependent upon the location of the filter devicesconcerned relative to the application area in which the fluid paintoverspray enters the stream of crude gas, the concentration factor, i.e.the proportion of fluid paint overspray to the entire amount of materialpresent in the respective auxiliary material reservoir, differs greatlyfrom auxiliary material reservoir to auxiliary material reservoir. Thefluidity of the concentrated auxiliary-material/paint-mixture differsaccordingly. If the suction process in just one auxiliary materialreservoir is no longer being implemented correctly, then this leads toan interruption of the process and requires manual intervention. Thetimes for the material exchange must be set individually for eachauxiliary material reservoir and they have to be selected in such a waythat one can be certain of being above the critical range ofconcentration of fluid paint overspray. This means a high consumption ofmaterials, both of fresh auxiliary material as well as auxiliarymaterial loaded with fluid paint overspray, and in consequence highexpenditure for the storage and the transportation of the auxiliarymaterial.

In contrast thereto, just one reservoir has to be monitored in regard tothe quantity of material therein and the concentration factor thereof inthe case of the device described above for separating fluid paintoverspray for a plurality of filter devices through each of which thereis a partial stream of crude gas. Furthermore, due to the fact that thematerial cleansed from a plurality of different filter devices ismechanically mixed, it becomes possible to compensate for particularlyhigh concentrations of fluid paint overspray in the material cleansedfrom a certain filter device by mixing it with material that is lessloaded with fluid paint overspray and which has been cleansed from otherfilter devices. In consequence, the material present in the largerreservoir can be concentrated to a higher level of concentration offluid paint overspray without impairing the fluidity of the mixtureconsisting of auxiliary material and fluid paint overspray.

Moreover, the constructional outlay required for the production of asingle large reservoir is much less than the outlay required for theproduction of many small auxiliary material reservoirs each of which isassociated with just one filter device.

Due to the larger interior space of the reservoir associated with aplurality of filter devices, it is also more easily possible toaccommodate a suitable mixing device in the interior space of thereservoir.

Preferably, the reservoir is in the form of a trough which extends froma region located vertically below a first filter device up to a regionlocated vertically below a second filter device, whereby in principle asmany further filter devices as desired may be arranged between the firstfilter device and the second filter device.

In a preferred embodiment of the invention, provision is made for thereservoir to accommodate material that has been cleansed from at leastthree different filter devices.

The mixing device preferably comprises at least one mixing tool that isrotatable about a substantially horizontally oriented axis of rotation.Thorough mixing of the material contained in the reservoir along thedirection of the axis of rotation is thereby obtained so that thematerial in the reservoir does not exhibit differences of concentration.

In order to enable thorough mixing to also be achieved in longreservoirs for accommodating the material cleaned off the filterelements of a plurality of filter devices, provision may be made for themixing device to comprise at least two shafts which are rotatable abouta substantially horizontally oriented axis of rotation and which arearranged one behind the other along the axis of rotation.

By the use of a plurality of shorter shafts instead of just a singlelong shaft for holding the mixing tools, the drive power necessary forthe production of the rotary motion of the mixer tools can be reduced.

In order to destroy the binding forces between the particles of thematerial present in the reservoir, the mixing device may be providedsuitable mixer tools as desired.

In particular, provision may be made for the mixing device to compriseat least one paddle, at least one ploughshare and/or at least one helix,screw or spiral.

For thorough mixing of the material disposed in the reservoir, it isexpedient, if the mixing device comprises at least two helices havingopposite directions of rotation.

Since a classifying effect whereby fine components of the material arecarried out of the storage tank does not occur as a result of themechanical mixing of the material in the reservoir, the particle sizedistribution of the auxiliary material in the case of the devicedescribed may be selected in such a way as to result in as large asurface area as possible which embeds and thus de-bonds the fluid paintparticles.

In particular, an auxiliary material may be used in which at least 20percent by weight of the particles have a particle size of less than 2μm.

The density of the auxiliary material being used, such as stone dust forexample, may amount to approximately 2.75 g/cm³ for example.

Auxiliary materials that are also usable in the device described areones having bulk material properties which are to be described ascohesive.

If the reservoir comprises a material outlet opening for extractingauxiliary material loaded with fluid paint overspray from the reservoir,then it is expedient if the mixing device comprises a mixing tool whichassists the discharge of the material through the material outlet.

Furthermore, the reservoir may comprise an inlet for fresh auxiliarymaterial in order to reduce the concentration of fluid paint oversprayin the material in the reservoir by supplying fresh auxiliary materialthereto.

Preferably the inlet for fresh auxiliary material is arranged in a firstend region of the reservoir and the reservoir comprises a materialoutlet opening which is arranged in a second end region of the reservoirthat is located opposite the first end region.

Particularly thorough mixing of the material disposed in the reservoiris achieved if the mixing device sweeps over a mixing region in thecourse of a complete revolution and the reservoir comprises a mixingsection having an internal contour corresponding to the outer contour ofthe mixing region.

It is particularly expedient if the reservoir comprises a mixing sectionand if the mixing device sweeps over substantially the entire mixingsection of the reservoir in the course of a complete revolution.

Provision is preferably made hereby for substantially the entire amountof material that is accommodated in the reservoir to be located in themixing section of the reservoir in the normal operation of the device.

The mixing section of the reservoir may, in particular, be substantiallycylindrical or in the form of a section of a cylinder.

The reservoir is preferably arranged vertically directly below thefilter devices from which the reservoir receives the cleansed material.

Furthermore, provision may be made for the partial streams of crude gasto be at least partially fed through the reservoir in order to pick upauxiliary material from the reservoir.

Furthermore, provision may be made for a stream of a medium that forms alayer differing from a paint used for painting the workpieces to beapplicable by means of the application unit of at least one paintingdevice of the paint shop for the purposes of applying a layer to asurface.

Thereby, a painting device is provided which is employable in a flexibleand space-saving manner and which incorporates as small a number ofcomponents as possible.

In this case for example, due to the fact that a stream of a medium thatforms a layer differing from a paint used for painting the workpieces isapplicable by means of the application unit, a layer can be applied to asurface that is not to be painted by means of the painting device in asimple manner. It is thereby possible to dispense with separate coatingdevices. In consequence, the painting device comprises a smaller numberof components.

In one embodiment of the invention, provision is made for theapplication unit to comprise a paint applicator for applying paint tothe workpieces that are to be painted, whereby the medium forming alayer differing from the paint used for painting the workpieces isapplicable by means of said applicator.

As an alternative or in addition thereto, provision may be made for theapplication unit to comprise a medium delivery assembly for deliveringthe layer-forming medium in addition to the paint applicator.

It is advantageous, if the painting device comprises a switching deviceby means of which a paint supply line or a medium supply line isselectively connectable to the paint applicator.

In particular, provision may be made for the paint applicator tocomprise a delivery line for delivering paint or medium into which apaint supply line or a medium supply line selectively flows. One therebydispenses with the need to provide separate paint and medium deliverylines.

It is expedient, if the painting device comprises a reservoir into whichpaint that is still disposed in the delivery line and/or medium that isstill disposed in the delivery line when switching between a paintdelivery mode and a medium delivery mode is feedable. In this way, onecan prevent a workpiece that is to be painted from being contaminatedwith a layer-forming medium that is still disposed in the delivery lineor a surface to which a layer-forming medium is to be applied from beingcontaminated with paint that is still disposed in the delivery line.

In order to provide a surface that is not to be painted with aprotective layer in a particularly simple way, provision is preferablymade for the surface that is not to be painted to have the layer-formingmedium applicable thereto by means of the application unit.

In particular, provision may be made for a surface that is locatedoutside the painting device itself, for example, a surface of a boundarywall of a paint booth to have the layer-forming medium applicablethereto by means of the application unit.

Preferably, all the areas attainable by the painting device are arrangedto have the layer-forming medium applicable thereto.

A simple way of supplying the painting device with the medium isensured, in particular, if the painting device comprises a storage tankfor the layer-forming medium.

Advantageously, the painting device comprises a pump for propelling astream of paint and/or a stream of medium that is to be supplied to theapplication unit.

In one embodiment of the invention, provision is made, apart from apaint and the layer-forming medium, for a cleaning medium for cleaning asurface and in particular for cleaning a surface contaminated with paintoverspray and/or a surface coated by means of the layer-forming medium,to also be applicable by means of the application unit.

Preferably, the cleaning medium is in the form of a fluid or is inparticulate form.

For the purposes of assisting a manual cleaning process, provision ispreferably made for the automatic application of a cleaning medium orthe washing-off of a manually applied cleaning medium by means of thepainting device.

For example, provision may be made for a high-pressure water jet to beapplicable by means of the application unit for the purposes ofcleansing a surface. A contaminated surface can thus be cleaned in aparticularly simple way. To this end for example, a high pressurecleaner may be arranged on the application unit, said cleaner preferablybeing displaceable by means of a moving device and being displaceable inparticular together with the application unit.

In order to prevent high air humidity in the environment of the paintingdevice from the very beginning, provision may be made for a cleaningprocess to be effected with a gaseous medium.

In one embodiment of the invention, provision is made for thelayer-forming medium to comprise a layer-forming material which picks upa liquid component of the paint used for painting the workpieces andforms together with the paint an easily cleanable layer. By applying thelayer-forming medium to a surface that is not to be painted, it can beensured that in operation of the painting device, paint particles,so-called paint overspray, which are not adhering to the vehicle bodiesbut are hitting the surface that is not to be painted will not adherepermanently to this surface but will be cleanable therefrom in a simplemanner.

As an alternative or in addition thereto, provision may be made for thelayer-forming medium to comprise a substance which incorporates at leastone chemically reactive group which can react with the paint, and inparticular with the paint overspray.

It is expedient, if the at least one chemically reactive group is anamine group.

It is particularly expedient, if the layer-forming medium comprises atleast one bi-functional amine.

In particular in the case where a bonding agent of the paint is at leastbi-functional, there is an advantageous reaction between thelayer-forming medium and the paint, for example by the formation of anetwork.

For example, one or more of the following reactions may occur:

a) reaction of an isocyanate with an amine

b) reaction of an amine with an epoxide

c) reaction of an amine with a carbonic acid

It is particularly expedient, if the layer-forming substance changesfrom a gel-like state into a film-like and in particular a solidfilm-like state by reaction with the paint.

As material for surface protection purposes, an auxiliary material or aprecoat material which forms a protective layer on the surface to whichit is applicable by means of the painting device is particularlysuitable.

Furthermore, provision may be made for surfaces that are to beprotected, and in particular those of robots, transporting axles,gratings, etc., to be coated once only or at regular intervals with fat,Vaseline, peel-off paint, a nano-coating and/or a non-stick coating bymeans of the application unit.

As an alternative or in addition thereto, provision may be made fornano-lacquers which use the lotus effect for example to be applicable tosurfaces that are to be protected by means of the application unit forthe purposes of simplifying or avoiding the cleaning process.

Furthermore, provision may be made for a drying medium, for example agas or a gas mixture, for drying a previously painted workpiece or asurface that has been previously cleaned with an e.g. aqueous cleaningmedium to be deliverable to the workpiece or the cleaned surface bymeans of the application unit.

It is expedient, if the painting device comprises a moving device forthe motorised conveyance of the application unit.

It is particularly expedient, if the moving device for the motorisedconveyance of the application unit is in the form of a robot.

Advantageously, the painting device comprises control equipment forcontrolling the moving device. In particular, it is thereby possible toautomate the operation of the painting device.

The painting device described is suitable in particular for use in apaint shop which comprises a paint booth.

The paint shop described may exhibit the features and advantages thathave been described hereinabove in connection with the painting devicedescribed.

In particular, in combination with a dry washing process for cleaning anair flow contaminated with paint overspray, provision may be made forthe application unit of the painting device to take on further functionsover and above that of painting.

Thus, the painting device is preferably suitable for applying aprotective layer to a wall surface of a paint booth, a conveying deviceand/or a flow chamber.

A simplified cleaning process is obtained especially when using acombination of different media, and in particular from an atomizer,which are applied to different areas of the paint booth, for example,the windows, walls, gratings, transporting axles, floor areas, robotcomponents, the conveying device, areas under the plane of the gratingand/or the painting device itself.

Preferably, the paint booth can be provided with a complete or at leastwith a partial coating of a peel-off foil and/or Vaseline by means ofthe painting device.

In one embodiment of the paint shop, a filter for cleaning air ladenwith paint overspray is provided underneath the paint booth, the filterelements of said filter being provided with a layer of an auxiliarymaterial or a pre-coat material and said filter comprising a funnel forcollecting the auxiliary material or pre-coat material cleaned off thefilter elements. In order to prevent coarse impurities resulting from aprocess of cleaning the paint shop from entering the filter and toprevent the auxiliary material or the pre-coat material in the filterfrom being excessively contaminated, provision is preferably made for anair-permeable filter mat to be arranged at an inlet of the filter which,for example, forms a bottleneck for an air flow, whereby said filter matcloses the inlet of the filter.

Furthermore, the features and advantages specified hereinafter maypreferably form a component part of the present invention:

-   -   a reduced expenditure on personnel is ensured by automated        operation of the painting device;    -   a lesser expenditure on cleaning and thus more economical        operation of the paint shop arises as a result of a simplified        cleaning process and/or reduced contamination of the paint shop;    -   disposal costs can be saved due to the prevention of heavy        contamination of the auxiliary material or precoat material.

Furthermore, provision may be made for the device for separating fluidpaint overspray from the stream of crude gas containing oversprayparticles to comprise at least one filter device for separating fluidpaint overspray from the stream of crude gas containing oversprayparticles, which comprises

-   at least one filter element for separating the overspray from the    stream of crude gas and-   at least one auxiliary material reservoir for accommodating an    auxiliary material which is supplied to the stream of crude gas    loaded with fluid paint overspray before the stream of crude gas has    passed at least one filter element for separating the overspray from    the stream of crude gas, wherein the auxiliary material reservoir is    provided with a balance.

Such a construction of the auxiliary material reservoir makes itpossible to monitor the current operational state of the auxiliarymaterial reservoir in a simple manner in order, in particular, to enablethe process of emptying-out a mixture of auxiliary material and fluidpaint overspray from the auxiliary material reservoir to be controlledin a purposeful manner.

Furthermore, provision may be made for the device for separating fluidpaint overspray from the stream of crude gas containing oversprayparticles to comprise at least one filter device for separating fluidpaint overspray from the stream of crude gas containing oversprayparticles, which comprises

-   at least one filter element for separating the overspray from the    stream of crude gas and-   at least one auxiliary material reservoir for accommodating an    auxiliary material, wherein the filter device comprises at least one    inlet opening through which the stream of crude gas enters the    filter device and-   wherein the inlet opening is bounded upwardly by an upper guidance    element which incorporates at least one passage opening.

This offers the advantage that auxiliary material from the filter devicecan reach a lower guidance element through at least one passage openingin the upper guidance element, the inlet opening of the filter devicebeing bounded in the downward direction by said lower guidance elementupon which paint drops may fall in operation of the filter device,whereby said drops separate from the lower guidance element (from alower intake slope for example) and fall into the auxiliary materialreservoir and could settle therein on sinter plates provided for thefluidisation of the material in the auxiliary material reservoir.

However, due to the auxiliary material reaching the lower guidanceelement of the inlet opening from the filter device through the at leastone passage opening in the upper guidance element, the paint particleswhich could deposit on the lower guidance element are de-bonded andcoated with the auxiliary material and thus made harmless.

The auxiliary material can, in particular, reach the lower guidanceelement through the at least one passage opening in the upper guidanceelement when the filter element is being cleaned and the blown-offmixture consisting of auxiliary material and fluid paint overspray(filter cake) falls from the cleansed filter element through the atleast one passage opening in the upper guidance element onto the lowerguidance element.

Furthermore, the present invention relates to an auxiliary materialreservoir for use in particular in a paint shop in accordance with theinvention, said reservoir accommodating an auxiliary material which issupplied to a stream of crude gas loaded with fluid paint overspraybefore the stream of crude gas has passed at least one filter elementfor separating the overspray from the stream of crude gas, wherein theauxiliary material reservoir is provided with a balance.

This embodiment of the auxiliary material reservoir makes it possiblefor the current operational state of the auxiliary material reservoir tobe monitored in a simple way in order, in particular, to enable theprocess of emptying-out a mixture consisting of auxiliary material andfluid paint overspray from the auxiliary material reservoir to becontrolled in a purposeful manner.

In order to enable the weight of the mixture of auxiliary material andfluid paint overspray that is contained in the auxiliary materialreservoir to be determined as precisely as possible, it is expedient forthe auxiliary material reservoir to comprise a lower section which ismechanically decoupled from an upper section of the auxiliary materialreservoir.

This mechanical decoupling can be obtained for example, by the provisionof a compensator between the lower section and the upper section of theauxiliary material reservoir.

In particular, such a compensator may be formed from a flexiblematerial, for example, from a flexible plastic material.

Furthermore, it is expedient if the weight of the lower section of theauxiliary material reservoir and of the material contained therein isdeterminable by means of the balance.

Furthermore, the present invention relates to a filter device forseparating fluid paint overspray from a stream of crude gas containingoverspray particles particularly for use in a paint shop in accordancewith the invention, wherein the filter device comprises

-   at least one filter element for separating the overspray from the    stream of crude gas and-   at least one auxiliary material reservoir for accommodating an    auxiliary material, wherein the filter device comprises at least one    inlet opening through which the stream of crude gas enters the    filter device, and wherein the inlet opening is bounded upwardly by    an upper guidance element which incorporates at least one passage    opening.

It is particularly expedient, if the inlet opening is bounded downwardlyby a lower guidance element and if auxiliary material from the filterdevice can reach the lower guidance element through at least one passageopening in the upper guidance element. In this way auxiliary materialand especially auxiliary material that has been cleaned off a filterelement of the filter device can reach the lower guidance element of theinlet opening of the filter device in a simple manner, whereby the paintparticles settling on said guidance element are de-bonded and/or can becoated with the auxiliary material so that these paint particles can nolonger fall into the auxiliary material reservoir and then settle on thesinter plates for the fluidisation process.

It is particularly advantageous, if the upper guidance elementincorporates a plurality of passage openings through which auxiliarymaterial from the filter device can reach the lower guidance element.

In particular, provision may be made for the upper guidance element tocomprise a passage region in which the passage openings are arranged,wherein the passage openings cover at least 25% of the surface area ofthe passage region.

The passage openings may, in particular, be arranged in the passageregion of the upper guidance element in a regular pattern, for example,in a rectangle or a square lattice.

Furthermore, the present invention relates to a method of operating apaint shop, in particular for the operation of a paint shop inaccordance with the invention, which comprises the following methodsteps:

-   -   applying fluid paint to workpieces and in particular to vehicle        bodies that are to be painted, by means of at least one        application unit of at least one painting device;    -   introducing a stream of crude gas containing overspray particles        into a filter device, and in particular into a filter device in        accordance with the invention; and    -   separating the overspray from the stream of crude gas by means        of at least one filter element that is arranged in the filter        device.

Such a method makes it possible to remove fluid paint overspray thatresults from the application of fluid paint to the workpieces that areto be painted and has been picked up by an air flow passing through theapplication area from this air flow and then feed the cleansed air flowback to the application area in an air re-circulating system or elseexpel it to the environment of the paint shop.

In a special embodiment of such a method, provision may be made for thestream of crude gas to be fed into the filter device through at leastone inlet opening in such a way that the stream of crude gas enters thefilter device so as to be directed into an auxiliary material reservoirfor accommodating an auxiliary material. Hereby, the at least one filterelement can be subjected to auxiliary material in a simple and efficientmanner, without such auxiliary material entering the application area ofthe paint shop.

It is particularly expedient, if the stream of crude gas is diverted inan interior space of the auxiliary material reservoir.

Preferably, the average rate of flow of the stream of crude gas whenpassing the narrowest part of the inlet opening amounts to at leastapproximately 2 m/s.

Furthermore, provision is preferably made for the stream of crude gas tobe introduced into the filter device in such a way that the stream ofcrude gas does not break-away in the vicinity of the inlet opening.

The stream of crude gas emerging from the inlet opening is preferablydiverted in the auxiliary material reservoir towards the at least onefilter element.

Furthermore, provision may be made for the auxiliary material present inthe auxiliary material reservoir to be whirled up by means of at leastone fluidising device.

Preferably, the stream of crude gas flows through a flow chamber from anapplication area for applying the fluid paint to the objects that are tobe painted up to the at least one inlet opening of the at least onefilter device.

Hereby, provision may be made for the rate of flow of the stream ofcrude gas to increase continuously when flowing through the flowchamber.

Furthermore, provision may be made in the case of the method describedfor an auxiliary material to be supplied to the stream of crude gasloaded with fluid paint overspray,

wherein the auxiliary material is disposed at least partially in anauxiliary material reservoir and the level of the auxiliary material inthe auxiliary material reservoir is determined by means of a levelsensor. In such a method, the operational state of an auxiliary materialreservoir which receives the auxiliary material cleaned off the at leastone filter element is monitored individually in order to enable, inparticular, the time point for the emptying of the auxiliary materialreservoir to be matched as precisely as possible to the operationalstate of the auxiliary material reservoir.

Hereby, provision may be made, in particular, for the level sensor toproduce a signal which corresponds to a value from a multiplicity ofdiscrete height levels or from a continuum of height levels.

In particular, provision may be made for the level sensor to produce ananalogue signal.

In particular, a capacitive sensor may be used as the level sensor.

In a preferred embodiment of the method, provision is made for theauxiliary material in the auxiliary material reservoir to be fluidisedby supplying a gaseous medium to an interior space of the auxiliarymaterial reservoir.

Furthermore provision may be made for the auxiliary material in theauxiliary material reservoir to be whirled up by means of a fluidisingdevice.

It is particularly expedient, if the level sensor and the fluidisingdevice are removed together from an interior space of the auxiliarymaterial reservoir.

Furthermore, provision may be made for a median cone of gaseous mediumthat has been produced by means of the fluidising device to sweep oversubstantially the entire extent of a base surface of the auxiliarymaterial reservoir.

Preferably, the material present in the auxiliary material reservoir isthoroughly mixed.

Furthermore, provision may be made in the case of the method ofoperating a paint shop for an auxiliary material to be introduced intothe flow path of a stream of crude gas loaded with fluid paint overspraybefore the stream of crude gas passes at least one filter element forseparating the overspray from the stream of crude gas, and furthermore,for the method to comprise the following method steps:

-   -   determining as to whether there is an adequate flow of crude gas        through the at least one filter element; and    -   blocking the introduction of auxiliary material into the flow        path of the stream of crude gas if it is established that the        flow of crude gas is inadequate.

Consequently, introduction of auxiliary material into the applicationarea of the paint shop is reliably prevented even when the system is notfunctioning correctly.

If the process of introducing auxiliary material into the flow path ofthe stream of crude gas is effected by whirling up the auxiliarymaterial present in an auxiliary material reservoir by means of afluidising device, then the functioning of the fluidising device ispreferably blocked in the absence of an adequate flow of crude gas.

If the process of introducing auxiliary material into the flow path ofthe stream of crude gas is effected by cleansing auxiliary material fromat least one filter element, then the process of cleaning the at leastone filter element is preferably blocked in the absence of an adequateflow of crude gas.

If the process of introducing auxiliary material into the flow path ofthe stream of crude gas is effected by supplying it by means of a nozzleassembly, then the functioning of the nozzle assembly is preferablyblocked in the absence of an adequate flow of crude gas.

For the purposes of establishing the absence of an adequate flow ofcrude gas, there are many possibilities.

Thus for example, provision may be made for the absence of an adequateflow of crude gas to be determined on the basis of the drop in pressureacross the at least one filter element. If the measured pressure drop istoo small, then an adequate flow of crude gas is not present.

As an alternative or in addition thereto, the absence of an adequateflow of crude gas can be determined on the basis of the operationalstate of a fan arranged downstream of the at least one filter element.

To this end for example, the operational state of the fan may bemonitored by means of a current monitoring process, by means of afrequency converter and/or by means of a measurement of the decrease ofpressure across the fan.

As an alternative or in addition thereto, the absence of an adequateflow of crude gas can also be determined by means of a volumetric flowmeter which may, in particular, be arranged downstream of the at leastone filter element.

The method described extends the processing stability of the system inthe event of malfunctions and serves to protect sensitive components inthe equipment when operational breakdowns occur.

The method described is suitable for use in a dry fluid paint oversprayprecipitation system for paint booths in the automobile industry and inmore general industrial paint shop areas in order to maintain thepainting process and prevent or at least reduce damage.

Furthermore, provision may be made for the method of operating a paintshop to comprise the following method steps:

-   -   dividing the stream of crude gas into at least two partial        streams of crude gas which enter at least two different filter        devices through different inlet openings, wherein each filter        device comprises at least one filter element for separating the        overspray from the respective partial stream of crude gas;    -   separating the overspray from the partial streams of crude gas        by means of the filter elements;    -   cleaning material off the filter elements of a plurality of        different filter devices;    -   catching the cleansed material from the plurality of different        filter devices in the same reservoir;    -   mechanically mixing the material cleansed from the plurality of        different filter devices in the reservoir by means of a mixing        device.

It is thereby possible to maintain adequate fluidity of the mixtureconsisting of auxiliary material and fluid paint overspray cleaned offthe filter elements in the reservoir in a simple and efficient manner.

Thereby, the storage tank is preferably arranged directly verticallybelow the filter devices from which the reservoir receives the cleansedmaterial.

Furthermore, provision may be made for the partial streams of crude gasto be fed at least partly through the reservoir in order to thereby pickup auxiliary material from the reservoir.

Furthermore, provision may be made for the method of operating a paintshop to comprise the following method step:

-   -   delivering a medium forming a layer that differs from the paint        for painting the workpieces for the purposes of applying a layer        to a surface by means of the application unit.

Consequently, there is provided a method for the operation of a paintingdevice which is employable in a flexible manner and is capable of beingcarried out in a small area using as small a number of components aspossible, since both paint and a medium forming a layer differing fromthe paint are delivered by means of the application unit.

In a special embodiment of this method, provision is made for a surfacethat is located outside the painting device itself to be coated by meansof the medium.

It is expedient, if a chemical reaction takes place between thelayer-forming medium and the paint, and in particular between thelayer-forming medium and the paint overspray.

It is particularly expedient, if the layer-forming substance changesfrom a gel-like state into a film-like state.

The chemical reaction may take place, in particular, between a substanceof the layer-forming medium comprising an amine group and the paint.

Furthermore, provision may be made in the method of operating a paintshop for an auxiliary material to be supplied to the stream of crude gasloaded with fluid paint overspray,

wherein a mixture of auxiliary material and fluid paint overspray isdisposed in an auxiliary material reservoir and the weight or the massof the mixture in the auxiliary material reservoir is determined bymeans of a balance.

Hereby in particular, the balance may be coupled to a lower section ofthe auxiliary material reservoir which is mechanically decoupled from anupper section of the auxiliary material reservoir.

Furthermore, the weight or the mass of the lower section of theauxiliary material reservoir and of the material contained therein ispreferably determined by means of the balance.

In order to be able to judge the continued usefulness of the materialcontained in the auxiliary material reservoir for the purposes ofcoating the at least one filter element with a protective layer,provision may be made for the material to be whirled up from theauxiliary material reservoir in at least one whirling-up phase and forthe cleaning capacity or effectiveness of the material contained in theauxiliary material reservoir to be determined by a comparison of theweight or the mass of the material contained in the auxiliary materialreservoir before the whirling-up phase and after the whirling-up phase.

The “effectiveness” is a measure for the ability of the material toadhere to the filter element and bind to fluid paint overspray.

Such an effectiveness can be determined, in particular, as the quotientof the reduction of the weight or the mass of the material contained inthe auxiliary material reservoir due to the fluidising or whirling-upprocess and the net fluidising time.

For the purposes of determining the effectiveness with greaterprecision, provision may be made for a whirling-up cycle to be effectedwith a plurality of whirling-up phases that are separated from eachother by whirling-up pauses and for the weight or the mass of thematerial contained in the auxiliary material reservoir before the firstwhirling-up phase of the whirling-up cycle and after the lastwhirling-up phase of the whirling-up cycle to be compared for thepurposes of determining the effectiveness.

The larger the value for this effectiveness, the more suitable thematerial from the auxiliary material reservoir is for forming aprotective layer on the at least one filter element.

Consequently, it is expedient for material to be extracted from theauxiliary material reservoir if the determined effectiveness and/or thedetermined weight or mass difference falls below a given minimum value.

The extracted material, a mixture consisting of auxiliary material andfluid paint overspray, is replaced in this case by fresh auxiliarymaterial.

Furthermore, when cleaning at least one filter element of the at leastone filter device, provision may be made in the case of the method ofoperating a paint shop for auxiliary material to pass from the filterelement concerned through at least one passage opening in an upperguidance element which bounds an inlet opening of the filter device inthe upward direction to a lower guidance element which bounds the inletopening of the filter device in the downward direction.

Furthermore, the present invention relates to a method for manufacturinga device for separating fluid paint overspray from a stream of crude gascontaining overspray particles, which comprises the following methodsteps:

-   a) pre-assembling at least one unit for use in a device for    separating fluid paint overspray from a stream of crude gas    containing overspray particles at a point of manufacture, wherein    the unit comprises the following:    -   a filter element accommodating chamber for accommodating at        least one filter element for separating the overspray from the        stream of crude gas;    -   at least one auxiliary material reservoir for accommodating an        auxiliary material which is supplied to the stream of crude gas        before the stream of crude gas passes the at least one filter        element;    -   at least one partition wall for separating the filter element        accommodating chamber from a flow chamber of the device for        separating fluid paint overspray through which the stream of        crude gas flows before entering the unit; and    -   at least one inlet opening through which the stream of crude gas        enters the unit from the flow chamber;-   b) transporting the at least one pre-assembled unit from the point    of manufacture to an assembly point;-   c) arranging the at least one pre-assembled unit in a working    position at the assembly point.

A method of manufacturing a device for separating fluid paint oversprayfrom a stream of crude gas containing overspray particles which isfeasible in a particularly simple and rapid manner is thereby provided.

In accordance with the method described, the device for separating fluidpaint overspray may be built up in a simple manner from a number ofpre-assembled units which corresponds to the desired capacity.

In particular, provision may be made for the at least two pre-assembledunits to be manufactured at a point of manufacture, transported to theassembly point, arranged in a working position and connected to oneanother or to a partition wall that is arranged therebetween.

As a supplement thereto, the pre-assembled units may be connected to asupport structure of the application area of a paint shop.

The point of manufacture of the pre-assembled unit is preferably locatedoutside the building in which the device for separating fluid paintoverspray from a stream of crude gas is finally installed, and inparticular outside the factory site on which this device is installed.Preferably, the unit is pre-assembled at the factory site of amanufacturer and then transported via public traffic routes to thefactory site of the operator of the device for separating fluid paintoverspray from a stream of crude gas and there, it is built into thisdevice.

Furthermore, the present invention relates to a method for theconversion of an existing device for separating fluid paint oversprayfrom a stream of crude gas containing overspray particles whichcomprises a support structure for an application area, wherein themethod comprises the following method steps:

-   a) pre-assembling at least one unit for use in a device for    separating fluid paint overspray from a stream of crude gas    containing overspray particles at a point of manufacture, wherein    the unit comprises the following:    -   a filter element accommodating chamber for accommodating at        least one filter element for separating the overspray from the        stream of crude gas;    -   at least one auxiliary material reservoir for accommodating an        auxiliary material which is supplied to the stream of crude gas        before the stream of crude gas passes the at least one filter        element;    -   at least one partition wall for separating the filter element        accommodating chamber from a flow chamber of the device for        separating fluid paint overspray through which the stream of        crude gas flows before entering the unit; and    -   at least one inlet opening through which the stream of crude gas        enters the unit from the flow chamber;-   b) dismantling a part of the existing device so that the area    occupied by a pre-assembled unit in the working position thereof is    freed up;-   c) arranging a pre-assembled unit in the freed up working position;-   d) connecting the pre-assembled unit to the support structure for    the application area;-   e) repeating the steps b), c) and d) until all the pre-assembled    units are arranged in their working position and connected to the    support structure for the application area.

In this way, an existing device for separating fluid paint overspray canbe replaced by the modularly constructed device for a dry process ofprecipitating fluid paint overspray described above, without there beingany necessity to dismantle the application area of the paint shop forpainting workpieces, and in particular painting vehicle bodies, or theneed to erect a new steel structure for the application area.

Due to the variability in the height of the pre-assembled units and dueto the ability to set up two units that are mutually spaced in thetransverse direction of the device for precipitating fluid paintoverspray at an arbitrary distance from each other, a devicemanufactured in such a manner for separating fluid paint overspray canbe adapted to an application area of arbitrary dimensions in thelongitudinal direction and in the transverse direction.

In particular, it is possible to replace an existing device for a wetprocess of separating fluid paint overspray by means of a washingprocess by the modularly constructed device for a dry process ofseparating fluid paint overspray that has been described hereinabove.

Further features and advantages of the invention form the subject matterof the following description and the graphical illustration of exemplaryembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic perspective illustration of a paint booth witha device for separating fluid paint overspray from a stream of crude gascontaining overspray particles which is arranged underneath it and whichcomprises a flow chamber that is arranged below the paint booth andthree filter modules that are located on each side of the flow chamber;

FIG. 2 a schematic vertical cross section through the plant depicted inFIG. 1;

FIG. 3 a schematic vertical cross section corresponding to FIG. 2through the plant depicted in FIG. 1 wherein additionally, therespective directions of flow of the crude gas, the exhaust air emergingfrom the filter modules and the supply air being fed into the flowchamber for the production of transverse air curtains are indicated byarrows;

FIG. 4 a schematic plan view from above of the plant depicted in FIGS. 1to 3;

FIG. 5 a schematic side view of the plant depicted in FIGS. 1 to 4;

FIG. 6 a schematic perspective illustration of the device for separatingfluid paint overspray from a stream of crude gas containing oversprayparticles which is arranged underneath the paint booth of the plantdepicted in FIGS. 1 to 5 and which comprises transverse partition wallsthat divide the flow chamber into sections which follow each other inthe longitudinal direction of the flow chamber;

FIG. 7 a schematic perspective illustration of an individual filtermodule which is intended to be arranged between two neighbouring furtherfilter modules (central module);

FIG. 8 a schematic perspective illustration of an individual filtermodule which is intended to be arranged near a further filter module andwhich forms an end of a filter module row on the opposite side (cornermodule);

FIG. 9 a schematic vertical cross section through a filter module;

FIG. 10 a schematic vertical cross section through a filter module andthe adjoining region of the flow chamber within which the respectivelocal direction of flow of the stream of crude gas is indicated byarrows;

FIG. 11 a schematic perspective illustration of an edge region of aninlet opening of a filter module;

FIG. 12 a schematic front view of a filter module;

FIG. 13 a schematic vertical section through an auxiliary materialreservoir having a level sensor and a fluidising device arranged in theinterior of the container;

FIG. 14 a schematic side view of an inspection door of the auxiliarymaterial reservoir depicted in FIG. 13, together with a level sensor anda fluidising device that are held on the inspection door;

FIG. 15 a schematic plan view of the exterior of the inspection doordepicted in FIG. 14;

FIG. 16 a schematic plan view from above of a collector grid that isarranged in the auxiliary material reservoir depicted in FIG. 13;

FIG. 17 a schematic illustration of a device for supplying freshauxiliary material from a storage tank to auxiliary material reservoirsof the type illustrated in FIG. 13 that are in their working position;

FIG. 18 a schematic illustration of a removal device for removingauxiliary material mixed with overspray from the auxiliary materialreservoirs to a collecting tank;

FIG. 19 a schematic illustration of a filter module and of an exhaustair duct with a fan which are arranged downstream of the filter moduleas well as various devices for monitoring the operational state of thefan and a device for supplying compressed air to the filter elements, toa fluidising unit and to a fluid base of the filter module;

FIG. 20 a schematic vertical cross section through a second embodimentof a device for separating fluid paint overspray from an exhaust airstream containing overspray particles which comprises inclined flowguide plates for guiding a transverse air flow and an accessible gangwayhaving an inclined upper surface between the filter modules;

FIG. 21 a schematic vertical cross section through an alternativeembodiment of an auxiliary material reservoir which is provided with apneumatically operated agitator for mixing the material in the auxiliarymaterial reservoir and for homogenizing the contents;

FIG. 22 a schematic plan view from above of the auxiliary materialreservoir with a pneumatically operated agitator that is depicted inFIG. 21;

FIG. 23 a schematic vertical section through a further alternativeembodiment of an auxiliary material reservoir which is provided with anelectrically driven shaft and paddles for mixing the material in theauxiliary material reservoir and homogenizing the contents;

FIG. 24 a schematic plan view from above of the auxiliary materialreservoir with an electrically driven shaft that is depicted in FIG. 23;

FIG. 25 a schematic perspective illustration corresponding to FIG. 11 ofan edge region of an inlet opening in an alternative embodiment of afilter module in which the upper guide plate that bounds the inletopening in the upward direction is provided with a plurality of passageopenings;

FIG. 26 a schematic vertical section corresponding to FIG. 13 through analternative embodiment of an auxiliary material reservoir whichcomprises a lower section and an upper section that are mechanicallydecoupled by a compensator arranged therebetween, and is provided with acontainer balance;

FIG. 27 a schematic plan view corresponding to FIG. 15 of the exteriorof an alternative embodiment of an inspection door of the auxiliarymaterial reservoir;

FIG. 28 a schematic illustration corresponding to FIG. 17 of analternative device for supplying fresh auxiliary material from a storagetank to auxiliary material reservoirs located in their working position,wherein a storage tank of the device is mechanically decoupled from acellular rotary feeder of the device by means of a compensator and isprovided with a balance;

FIG. 29 a schematic cross section through a filter module and areservoir with a mixing device which is arranged beneath it;

FIG. 30 a schematic longitudinal section through three filter modulesthat succeed one another in a longitudinal direction of the paint shopand a reservoir with a mixing device which is arranged underneath thefilter modules;

FIG. 31 a schematic side view of a mixing device comprising two heliceshaving opposite directions of rotation which are rotatable about ahorizontal axis of rotation;

FIG. 32 a schematic side view of two groups each consisting of fourfilter modules, wherein each group of filter modules is associated witha reservoir having a mixing device for mixing material that has beencleansed from the filter modules of a respective group;

FIG. 33 a schematic side view of a group of eight filter modules,wherein a single long reservoir is associated with this large group offilter modules, and wherein the mixing device of said reservoir has twoshafts for holding mixing tools that are rotatable about a substantiallyhorizontally oriented axis of rotation, said tools being arranged onebehind the other in the direction of the axis of rotation;

FIG. 34 a schematic vertical cross section through a paint shop with anapplication unit arranged on a painting robot; and

FIG. 35 a schematic side view of the application unit depicted in FIG.34.

Similar or functionally equivalent elements are designated by the samereference symbols in each of the Figures.

DETAILED DESCRIPTION OF THE DRAWINGS

A plant for spray-painting vehicle bodies 102 which bears the generalreference 100 and is illustrated in FIGS. 1 to 19 comprises a purelyschematically illustrated conveyor device 104 by means of which thevehicle bodies 102 can be moved along a direction of conveyance 106through an application area 108 of a paint booth bearing the generalreference 110.

The application area 108 is the interior space of the paint booth 110which is bounded, in a horizontal transverse direction 112 runningperpendicularly to the direction of conveyance 106 which corresponds tothe longitudinal direction of the paint booth 110, on both sides of theconveyor device 104 by a respective booth wall 114.

Spraying mechanisms 116 in the form of painting robots for example, arelocated in the paint booth 110 on both sides of the conveyor device 104.

An air flow which passes substantially vertically downwardly through theapplication area 108 from above as is indicated in FIG. 3 by the arrows118 is produced by means of an (only sectionally illustrated) airre-circulating system.

This air flow picks up paint overspray in the form of oversprayparticles in the application area 108. Here, the term “particle”encompasses both solid and liquid particles, and in particular droplets.

When using fluid paint, the fluid paint overspray consists of paintdroplets. Most of the overspray particles have a largest dimensionfalling within a range of approximately 1 μm to approximately 100 μm.

The exhaust air stream loaded with the overspray particles from theapplication area 108 is referred to in the following as a stream ofcrude gas. The direction of flow of the stream of crude gas isrepresented in FIGS. 3 and 10 by arrows 120.

The stream of crude gas leaves the paint booth 110 downwardly and entersa device for separating fluid paint overspray from the stream of crudegas which bears the general reference 126 and is arranged beneath theapplication area 108.

The device 126 comprises a substantially parallelepipedal flow chamber128 which extends over the whole length of the paint booth 110 in thedirection of conveyance 106 and is bounded in the transverse direction112 by vertical side walls 130 which are in substantial alignment withthe lateral booth walls 114 of the paint booth 110 so that the flowchamber 128 has substantially the same horizontal cross-sectional areaas the paint booth 110 and is arranged substantially completely withinthe vertical projection of the surface area of the paint booth 110.

As can best be seen in FIG. 6, a plurality of e.g. three filter modules132 (also referred to as filter devices in the description hereinabove)are arranged in each case on both sides of the flow chamber 128 and formtwo rows of modules 136 that extend in the longitudinal direction 134(which coincides with the direction of conveyance 106) of the device 126for separating fluid paint overspray.

Each of the rows of modules 136 comprises two corner modules 138 whichform a respective end of a module row 136, and at least one centralmodule 140 which is arranged between two neighbouring filter modules132.

For the purposes of preventing longitudinal currents of the stream ofcrude gas in the longitudinal direction 134 of the flow chamber 128 andfor preventing the crude gas from flowing between the individual filtermodules 132, provision may be made for transverse partition walls 142which extend vertically in the transverse direction 112 and are eacharranged between two successive filter modules 132 in the longitudinaldirection 134 and which subdivide the flow chamber 128 into flow chambersections 144 that follow each other in the longitudinal direction 134.

Due to these transverse partition walls 142, it is possible to obtain adefined setting of the stream of crude gas for each individual filtermodule 132 independently of the stream of crude gas through the otherfilter modules 132.

Moreover, regions having different quantities of overspray or differenttypes of paint (for a purely type-separation process) can be separatedby the transverse partition walls 142.

As can best be seen in FIG. 2, a gangway 146 that is accessible to anoperator is provided between the two rows of modules 136.

In order to allow continuous access to the sections of the gangway 146that are arranged in the successive flow chamber sections 144, passagedoors 148 are provided in the transverse partition walls 142 (FIG. 6).

The end face walls 150 of the flow chamber 128 which close the flowchamber 128 at the front end and the rear end thereof are provided withentrance doors 152 through which an operator can enter the flow chamber128 from the outside.

Each of the filter modules 132 is in the form of a pre-assembled unit154 which is manufactured at a place that is located at a distance fromthe assembly point of the paint shop and transported as a unit to theassembly point of the paint shop. At the assembly point, thepre-assembled unit 154 is arranged in the intended working position andconnected to one or more neighbouring pre-assembled units 154 or to thetransverse partition walls 142 arranged therebetween as well as to asupport structure of the application area 108.

The construction of a filter module 132 is described hereinafter withreference to FIGS. 7 and 9 to 16 using the example of a central module140:

The module comprises a support structure 156 consisting of two verticalrear supports 158 and two vertical front supports 160 which are eachconnected at their upper ends by horizontal tie bars 162 to one of therear supports 158 (FIG. 7).

Furthermore, the front supports 160 are connected together at theirupper ends by means of a further (not illustrated) tie bar.

The rear supports 158 are also connected together by means of (notillustrated) tie bars or by means of a (not illustrated) connectingframework.

The tie bars at the upper end of the support structure 156 carry ahorizontal covering wall 164.

A vertical front wall 166 of the filter module 132 is held on the frontfaces of the front supports 160.

The covering wall 164 and the front wall 166 form partition walls 168 ofthe filter module 132 which separate a filter element accommodatingchamber 170 arranged within the filter module 132 from the region of theflow chamber 128 located outside the filter module 132.

In the filter element accommodating chamber 170 of the filter module132, there are a plurality of, ten for example, filter elements 172which are arranged in two rows above one another and project in thehorizontal direction from a common base body 174 which is held on therear faces of the rear supports 158.

The filter elements 172 may, for example, be constructed from plates ofsintered polyethylene which are provided on their outer surface with amembrane of polytetrafluorethylene (PTFE).

The coating of PTFE serves to increase the filter class of the filterelements 172 (i.e. to reduce their permeability) and furthermoreprevents permanent adherence of the fluid paint overspray that has beenseparated from the stream of crude gas.

Furthermore, the coating of the filter elements 172 contains anelectrically conductive component such as graphite for example, in orderto tap-off electrostatic charges from the filter elements 172 and ensureantistatic properties for the filter elements 172.

Both the base material of the filter elements 172 and the PTFE coatingthereof exhibit porosity so that the crude gas can enter through thepores into the interior space of the respective filter element 172.

Furthermore, in order to prevent the filter surfaces from stickingtogether, they are provided with a barrier layer consisting of theauxiliary material that is being introduced into the stream of crudegas. This preferably particle-like auxiliary material is also usuallyreferred to as a “precoat” material.

In operation of the device 126, the barrier layer is formed bydeposition of the auxiliary material that has been introduced into thestream of crude gas 120 onto the filter surfaces, and it prevents thefilter surfaces from sticking together due to the adhering fluid paintoverspray.

Auxiliary material from the stream of crude gas 120 also settles on theinterior surfaces of the covering wall 164 and the front wall 166 of thefilter module 132 where it likewise prevents adherence of fluid paintoverspray.

In principle, any medium can be used as the auxiliary material so longas it is capable of absorbing the liquid portion of the fluid paintoverspray and depositing itself on overspray particles and thus takingthe stickiness thereof.

In particular for example, chalk, stone dust, aluminium silicates,aluminium oxides, silicon oxides, powder coating or the like come intoconsideration as auxiliary materials.

As an alternative or in addition thereto, particles having a cavity-likestructure and an internal surface area that is large relative to theexternal dimensions thereof, such as zeolites or other hollow e.g.spherical bodies of polymers, glass or aluminium silicate and/or naturalor synthetically produced fibres for example could also be used as anauxiliary material for receiving and/or binding the overspray.

As an alternative or in addition thereto, particles which reactchemically with the overspray such as chemically reactive particles ofamine-, epoxide-, carboxyl-, hydroxyl or isocyanate groups, chemicallyreactive particles of aluminium oxide treated with octyl silane or solidor liquid mono-, oligo or polymers, silanes, silanole or siloxane couldalso be used as an auxiliary material for receiving and/or binding theoverspray.

A waste product from a production process such as a waste product fromthe processing of powder coatings or fine wood shavings or metal filingsresulting from a wood- or metalworking process for example could also beused as an auxiliary material.

The auxiliary material preferably consists of a multiplicity ofauxiliary material particles which have an average diameter fallingwithin the range of approximately 10 μm to approximately 100 μm forexample.

In order to enable the auxiliary material to be added to the stream ofcrude gas without the danger arising that the auxiliary material entersthe application area 108 of the paint shop 100, each filter module 132is provided with an auxiliary material reservoir 176 which is held onthe support structure 156 and has a funnel-like appearance in the shapeof an inverted frustum of a pyramid for example (FIG. 13).

The four trapezoidal side walls 178 of the auxiliary material reservoir176 are inclined to the vertical at an angle of at least approximately60°.

The height of the auxiliary material reservoir 176 amounts toapproximately 1.1 m for example.

The upper edges of the side walls 178 enclose an entrance opening 180 ofthe auxiliary material reservoir 176 through which the stream of crudegas loaded with overspray 120 can enter the auxiliary material reservoir176 and escape therefrom again.

The substantially horizontally oriented base 182 is in the form of aporous fluid base 184 which is flushable with a gaseous medium and inparticular with compressed air in order to fluidise the auxiliarymaterial disposed in the interior space 186 of the auxiliary materialreservoir 176 and locally equalize the different height levels of theauxiliary material within the auxiliary material reservoir 176.

When the plant 100 is operating, the fluid base is actuatedintermittently, for example, three times per minute for approximatelytwo seconds on each occasion.

In order to prevent the fluid base 184 from being damaged by fallinglarger objects, a collector grid or a retaining grid 187 is arranged ata distance of 20 cm for example above the fluid base 184, said gridextending in the horizontal direction over the entire cross section ofthe interior space 186 of the auxiliary material reservoir 176 andcomprising a plurality of rows of honeycomb or rectangular passageopenings 189 for the passage of auxiliary material through the retaininggrid 187. The passage openings are arranged such as to be mutuallydisplaced from row to row and have a size of approximately 30 mm×30 mmfor example (FIG. 16).

In order to allow access to the interior space 186 of the auxiliarymaterial reservoir 176 for maintenance purposes, one of the side walls178 is provided with an inspection opening which is closed during theoperation of the filter module 132 by an inspection door 188 having ahandle 190 (see FIGS. 13 to 15).

As can be seen in FIG. 15, the inspection door 188 is held in releasablemanner on the associated side wall 178 of the auxiliary materialreservoir 176 by means of clamps 192 with wing nuts 194.

A compressed air pipeline 196, which leads to a fluidising device 198,is held on the inspection door 188 (FIG. 14).

The fluidising device 198 serves to deliver blasts of compressed airinto the auxiliary material located below in order to whirl up thisauxiliary material and thereby introduce it into the flow of crude gasthat is being passed through the auxiliary material reservoir 176.

Moreover, due to the whirling up of the auxiliary material by means ofthe fluidising device 198, the mixture consisting of auxiliary materialand the overspray that is bound thereto which is present in theauxiliary material reservoir 176 is homogenised.

When the paint shop 100 is operating, the fluidising device 198 isactivated intermittently, for example, four times per minute forapproximately 5 seconds on each occasion.

The fluidising device 198 comprises a plurality of, two for example,outlet nozzles 200 for compressed air which are in the form of conicaljets and can each produce a cone of compressed air which widens outdownwardly towards the base 182 of the auxiliary material reservoir 176.

Preferably, the outlet nozzles 200 are constructed and arranged in sucha way that the compressed air cones produced by the outlet nozzles 200together sweep over the entire extent of the base surface of theauxiliary material reservoir 176.

Furthermore, a mounting plate 202 for a level sensor 204 is arranged onthe compressed air pipeline 196, said sensor comprising a rod-shapedsensor element 206 and a sensor housing 208 having the sensorelectronics accommodated therein (FIG. 14).

The level sensor 204 is in the form of an analogue and in particularcapacitive sensor and it serves to produce a signal which corresponds ineach case to a value from a multiplicity of discrete height levels orfrom a continuum of height levels in order to enable the level of theauxiliary material in the auxiliary material reservoir 176 to bedetermined in as precise a manner as possible.

The rod-shaped sensor element 206 of the level sensor 204 is orientedsubstantially vertically and is arranged as far as possible from theside walls 178 of the auxiliary material reservoir 176 in the proximityof the centre of the interior space 186 of the auxiliary materialreservoir 176 in order that the result of the measurement by the levelsensor 204 will be impaired as little as possible by edge effects (FIG.13).

The rod-shaped sensor element 206 of the level sensor 204 is orientedsubstantially vertically relative to the horizontal base 182 of theauxiliary material reservoir 176.

The signal that is produced by the level sensor 204 is transmitted overa (not illustrated) signal line to an electrical connection box 209 ofthe filter module 132 which is arranged on the base body 174 of thefilter elements 172 (see FIG. 7), and from there, it is conveyed to acontrol device of the paint shop 100 which is schematically illustratedin FIG. 19 and bears the reference 210.

In an alternative embodiment of an auxiliary material reservoir 176which is illustrated in FIG. 26, the quantity of the material that isaccommodated in the auxiliary material reservoir 176 is not determinedby a measurement of the liquid level, but rather, by a measurement ofthe weight.

To this end, the auxiliary material reservoir 176 is subdivided into anupper section 211 and a lower section 213, wherein the two sections areconnected together by a compensator 215 which is in the form of aring-like, closed, collar-like, flexible element which is connected onthe one hand to a mounting flange 219 at the lower end of the uppersection 211 and on the other hand to a mounting flange 221 at an upperend of the lower section 213 of the auxiliary material reservoir 176 bysuitable fixing means 217.

The compensator 215 may be formed from a flexible plastic material forexample.

The base 182 of the lower section 213 of the auxiliary materialreservoir 176 is in the form of a porous fluid base 184 as is the casefor the embodiment illustrated in FIG. 13.

The base 182 rests on a container balance 223 which is supported on afoundation by feet 225.

The material accommodated in the auxiliary material reservoir 176 (amixture of auxiliary material and fluid paint overspray that has beencleaned off the filter elements 172) is located entirely in the lowersection 213 of the auxiliary material reservoir 176 which ismechanically decoupled by the compensator 215 from the upper section 211and thus from the other components of the filter module 132

Consequently, the sum of the weights of the lower section 213 and thatof the material accommodated therein or—after an appropriate calibrationprocess—just the weight of the material accommodated in the lowersection 213 of the auxiliary material reservoir 176 is measurable bymeans of the container balance 223.

The container balance 223 produces an electrical measuring signal whichis transmitted over a (not illustrated) signal line to the electricalconnection box 209 of the filter module 132 which is arranged on thebase body 174 of the filter elements 172 (see FIG. 7), and from there,to a control device of the plant 100 which is schematically illustratedin FIG. 19 and bears the reference 210 therein.

Due to the presence of the container balance 223 in this embodiment ofthe auxiliary material reservoir 176, one can dispense with the levelsensor 204.

Furthermore, the fluidising device 198 may be held on the upper section211 of the auxiliary material reservoir 176 or on another component ofthe filter module 132 instead of on the inspection door 188.

Instead of the inspection door 188 illustrated in FIG. 15 which is heldin releasable manner on the associated side wall 178 of the auxiliarymaterial reservoir 176 by means of clamps 192 and wing nuts 194, aninspection door 188 of the type illustrated in FIG. 27 may therefore beused as an alternative, this door being held in pivotal manner on theassociated side wall 178 of the auxiliary material reservoir 176 bymeans of hinges 217 and being lockable in a closed position relative tothe side wall 178 of the auxiliary material reservoir 176 by means of alever 219 which is mounted in pivotal manner on the inspection door 188.

In both the case of the embodiment of an inspection door 188 illustratedin FIG. 15 and of that in FIG. 27, provision may be made for a (notillustrated) collecting pan for catching any dust that falls out of theauxiliary material reservoir 176 when the inspection door 188 is opened,said pan being located in front of the inspection opening that is closedby the respective inspection door 188 on the outer side of the auxiliarymaterial reservoir 176.

Furthermore, in order to specifically direct the stream of crude gasentering the filter module 132 into the interior space 186 of theauxiliary material reservoir 176 and yet prevent direct access of thestream of crude gas from the flow chamber 128 to the filter elements172, each filter module 132 is provided with a slot-like inlet opening212 which is in the form of an inlet channel 214 and for example, as canbe seen particularly in FIG. 9, it has a through-flow cross section thatnarrows in the direction of flow of the stream of crude gas up to anarrow section 240.

As an alternative or in addition thereto, provision may also be made forthe inlet channel 214 to have a through-flow cross section which widensout in the direction of flow of the stream of crude gas from the narrowsection 240.

The inlet channel 214 is bounded in the downward direction by an intakeslope 216 which extends upwardly at an angle from the front supports 160of the support structure 156 and is inclined at an angle of e.g.approximately 40° to approximately 65° to the horizontal, and also by alower guide plate 218 which adjoins the lower end of the intake slope216, said lower guide plate being inclined to the horizontal to agreater extent than the intake slope 216, for example, at an angle ofapproximately 55° to approximately 70° and it protrudes above an uppersubstantially vertically oriented section 220 of a side wall 178 of theauxiliary material reservoir 176 and projects into the interior space186 of the auxiliary material reservoir 176.

In this way, the lower guide plate 218 acts as a restraining element 222which keeps auxiliary material from the auxiliary material reservoir 176away from the inlet opening 212 and prevents whirled up auxiliarymaterial from leaving the auxiliary material reservoir 176 along theside wall 178 at the side of the inlet opening 212.

Moreover, the lower guide plate 218 prevents the stream of crude gasfrom breaking-away after passing the intake slope 216 and ensures adirected flow of the crude gas into the auxiliary material reservoir176.

The depth of the lower guide plate 218 (i.e. the extent thereof in thedirection of flow of the stream of crude gas) is approximately 100 mmfor example.

The intake slope 216 and the lower guide plate 218 extend in thelongitudinal direction 134 of the flow chamber 128 over substantiallythe entire length of the inlet opening 212 of approximately 1 m toapproximately 2 m for example, which almost corresponds to the extent ofthe entire filter module 132 in the longitudinal direction 134.

The upper surface of the intake slope 216 and the upper surface of thelower guide plate 218 together form a lower guidance surface 224 for theinlet opening 212 which bounds the inlet opening 212 downwardly, and inthe upper section 226 thereof which is formed by the intake slope 216 ithas an inclination of approximately 40° to approximately 65° to thehorizontal whereas in the lower section 228 thereof which is formed bythe lower guide plate 218 it has a greater inclination to the horizontalof approximately 55° to approximately 70°.

In the upward direction, the inlet opening 212 is bounded by the loweredge of the front wall 166 and by an upper guide plate 230 which isinclined downwardly from the lower edge of the front wall 166 andprotrudes into the interior space of the filter module 132.

In like manner to the lower guide plate 218, the upper guide plate 230is inclined to the horizontal at an angle of approximately 55° toapproximately 70° for example and it extends in the longitudinaldirection 134 over substantially the entire width of the inlet opening212 of 1 m or 2 m for example.

The depth of the upper guide plate 230 (i.e. the extent thereof alongthe direction of flow of the stream of crude gas) is approximately 150mm for example.

The lower side of the upper guide plate 230 forms an upper guidancesurface 232 which bounds the inlet opening 212 in the upward directionand is inclined to the horizontal at an angle of approximately 55° toapproximately 70° for example.

Due to this upper guidance surface 232 for the stream of crude gas, theeffect is achieved that the stream of crude gas does not break-away atthe front wall 166 of the filter module 132, but rather, it is guideddirectly into the auxiliary material reservoir 176.

Furthermore, the upper guide plate 230 serves as a filter shieldingelement 234 since it is configured and located at the inlet opening 212in such a way that it prevents the crude gas entering the filter module132 from flowing directly to the filter elements 172.

Furthermore, the upper guide plate 230 serves as a deflector element 236which keeps the material cleaned off the filter elements 170, thismaterial containing auxiliary material and overspray particles bound tothe auxiliary material, away from the inlet opening 212.

Rathermore, material falling down from the filter elements 172 onto theupper surface of the upper guide plate 230 is guided into the auxiliarymaterial reservoir 176 by the sloping arrangement of the upper guideplate 230.

In operation of the filter module 132, both the upper guidance surface232 and the upper surface of the upper guide plate 230 are provided witha coating of the auxiliary material so that these surfaces of the upperguide plate 230 are easily cleaned and overspray does not stick directlyto the upper guide plate 230.

As an alternative to a closed upper guide plate 230 however, an upperguide plate 230 such as is illustrated in FIG. 25 can be used, thishaving a plurality of passage openings 239 in a lower passage region 237which make it possible for the auxiliary material that has been cleanedoff the filter elements 172 to pass through these passage openings 239to the upper surface of the lower guide plate 218 and/or to the uppersurface of the intake slope 216.

The intake slope 216 and the lower guide plate 218 form a lower guidanceelement 241 which bounds the inlet opening 212 of the filter module 132downwardly, whilst the upper guide plate 230 forms an upper guidanceelement 243 which bounds the inlet opening 212 of the filter module 132in the upward direction.

The auxiliary material falling on the lower guidance element 241de-adheres paint particles which could deposit there, and it combineswith these paint particles so that they can no longer clog sinter platesof the fluid base 184 of the auxiliary material reservoir 176 if theyfall into the auxiliary material reservoir 176.

Preferably, the passage openings 239 in the upper guidance element 243cover at least 25% of the surface area of the passage region 237 of theupper guidance element 243.

The passage openings 239 may, for example, be rectangular orsubstantially square.

Furthermore, the passage openings 239 may be arranged in a regularpattern, for example, in a rectangular or a square lattice in thepassage region 237.

Furthermore, as can best be seen from FIG. 12, the filter module 132comprises two covering elements 238 in the form of approximatelytriangular cover plates which cover the left and the right lower cornerarea of the inlet opening 212 in such a way that auxiliary material andoverspray from the stream of crude gas are kept away from these cornerareas of the inlet opening 212 and deposition of auxiliary material andof overspray particles in these corner areas and outside the filtermodule 132 on the intake slope 216 is prevented.

The upper surfaces of the covering elements 238 are oriented at an angleto the vertical and at an angle to the horizontal and each has asurface-normal which is oriented upwardly into the outer area of thefilter module 132.

Due to the form of geometry of the inlet opening 212 described above,the effect is achieved that the inlet opening 212 has a narrow section240 at which the through-flow cross section of the inlet opening 212 isat its smallest and the speed of the crude gas is therefore at itsgreatest.

Preferably, the speed of the crude gas in the narrow section amounts toapproximately 2 m/s to approximately 8 m/s, and in particular, toapproximately 3 m/s to approximately 5 m/s.

Auxiliary material from the interior of the filter module 132, whichforms a closed box, is effectively prevented from entering the flowchamber 128 and from there, entering the application area 108 in thisway. The process of whirling up the auxiliary material in the auxiliarymaterial reservoir 176 and the process of cleaning the filter elements172 can therefore take place at any time, without one having tointerrupt the supply of crude gas to the filter module 132 or evenhaving to interrupt the operation of the paint spraying devices 116 inthe application area 108.

Furthermore, due to the fact that the stream of crude gas emerges fromthe inlet opening 212 directed into the auxiliary material reservoir176, it is ensured that a deflection of the stream of crude gas willtake place in the interior space 186 of the auxiliary material reservoir176. Consequently, an adequate quantity of auxiliary material, which isproduced by whirling up the contents of the auxiliary material reservoir176, is carried along by the stream of crude gas. Furthermore, auxiliarymaterial whirled up in the interior space 186 of the auxiliary materialreservoir 176 by means of the fluidising device 198 is carried out bythe stream of crude gas 120 from the auxiliary material reservoir 176 tothe filter elements 172.

The stream of crude gas from the flow chamber 128 through the inletopening 212 into the interior space of the filter module 132 isillustrated in FIG. 10 as the result of a flow simulation process. Fromthis, it is readily apparent that a rotary-drum-like flow, in which thehorizontally extending axis lies somewhat lower than the upper edge ofthe auxiliary material reservoir 176, is formed in the interior space ofthe filter module 132.

At the side of the auxiliary material reservoir 176 opposite the inletopening 212, the stream of crude gas, which is loaded with auxiliarymaterial, flows back out of the auxiliary material reservoir 176 and isthen distributed through the entire depth of the filter elementaccommodating chamber 170 so that turbulence occurs around the filterelements 172 and, due to the high dynamics imparted to the stream ofcrude gas in the narrow section 240, a homogeneous distribution of theauxiliary material on the individual filter elements 172 is ensured.

Since there are hardly any components of the filter module 132 in theflow path of the incoming stream of crude gas, contamination of suchcomponents due to the stickiness of the paint is prevented butnevertheless there is a flow through the filter elements 172 which isadvantageous to the filtration process.

Due to the fact that the average direction of flow of the stream ofcrude gas entering the filter module 132 through the narrow section 240is inclined to the horizontal at an angle of more than 40°, an air lock,which would lead to material that has been cleaned off the filterelements 172 being immediately sent back again to these filter elements172 and which could also lead to the formation of mutually opposed airvortices within the filter module 132, is prevented from forming in thelower region of the filter element accommodating chamber 170.

In order to enable two filter modules 132 that are arranged next to eachother in a row of modules 136 to be connected together in a simple andstable manner or to enable a filter module 132 to be connected to anadjacent transverse partition wall 142, the support structure 156 ofeach filter module 132 includes at least one rear support 158 whichcomprises a vertical, substantially flat contact surface 242 that isoriented in the transverse direction 112 and can be placed on acorresponding contact surface 242 of a neighbouring filter module 132 oron a neighbouring transverse partition wall 142 (FIG. 7).

Furthermore, passage openings 244 are provided in the contact surface242 for the passage of fixing means with the aid of which the rearsupport 158 serving as a connecting element 246 is connectable to aconnecting element 246 of a neighbouring filter module 132 or to aneighbouring transverse partition wall 142.

The rear support 158 serving as a connecting element 246 preferably hasan approximately U-shaped profile.

As can be perceived from FIG. 7, each central module 140 comprises tworear supports 158 having U-shaped profiles which serve as connectingelements 246 and the open sides thereof face each other so that thecentral module 140 is connectable on both sides to an adjacent furtherfilter module 132 or to a transverse partition wall 142.

As can be perceived from FIG. 8, each corner module 138 comprises onlyone rear support 158 having a U-shaped profile which is in the form of aconnecting element 246; the opposite rear support 158 a, which is to beconnected to neither a neighbouring filter module 132 nor to aneighbouring transverse partition wall 142, can, for example, have aT-shaped profile instead of a U-shaped profile for the purposes ofincreasing its mechanical rigidity.

In all other respects, the corner module 138 corresponds in regard tothe construction and functioning thereof with the central modules 140that have been described in detail hereinabove.

In the operative state of each filter module 132, the stream of crudegas 120 sweeps over the filter surfaces of the filter elements 172,whereby both the auxiliary material and the fluid paint overspray thatare both being carried along thereby are deposited on the filtersurfaces, and the filtered crude gas enters the interior spaces of thefilter elements 172 through the porous filter surfaces in the form of astream of exhaust air, these interior spaces being connected to a cavitywithin the base body 174 from which the filter elements 172 project.From this cavity, the stream of cleansed exhaust air enters a respectiveexhaust air pipe 248 which leads from the base body 174 of the filterelements 172 of each filter module 132 to an exhaust air duct 250 thatis arranged approximately centrally under the flow chamber 128 and runsparallel to the longitudinal direction 134 of the flow chamber 128 (seein particular, FIGS. 2 and 3).

A flap 251, by means of which the volumetric air flow is adjustable bythe relevant filter module 132, is arranged in each exhaust air pipe 248

As can be perceived from the schematic illustration of FIG. 19, theexhaust air that has been cleansed of fluid paint overspray passes fromthe exhaust air duct 250 to an exhaust air fan 252, and from there, thecleansed exhaust air is supplied via a (not illustrated) cooling stackand a (not illustrated) supply line to a (not illustrated) air chamber,the so-called plenum, which is arranged above the application area 108.

From this air chamber, the cleansed exhaust air re-enters theapplication area 108 via a filter cover.

A (not illustrated) exhaust air line, through which a portion of thecleansed exhaust air stream is conveyed to the environment (through achimney for example), branches off from the supply line.

That part of the exhaust air stream that has been conveyed away to theenvironment is replaced by fresh air which is fed into the flow chamber128 via two air curtain producing devices 254 that are connected via arespective air supply line 256 to a (not illustrated) air supply system(FIGS. 1 to 3).

Each of the air curtain producing devices 254 comprises a respective airsupply chamber which extends in the longitudinal direction 134 of theflow chamber 128 and is fed with a supply of air via the supply line256, said chamber opening out through a gap 258, which extends in thelongitudinal direction 134 whilst the extent thereof in the verticaldirection lies in a range of approximately 15 cm to approximately 50 cmfor example, into an upper section 260 of the flow chamber 128 which isbounded in the upward direction by the application area 108 and by thecovering walls 164 of the filter modules 132 in the downward direction.

The gap 258 of each air supply chamber is arranged just above thecovering walls 164 of the filter modules 132 so that an air curtain willbe formed on the upper surface of the filter modules 132 by the inflowof air, which is being supplied from the air supply chambers, into theflow chamber 128 in a substantially horizontal direction along the uppersurfaces of the covering walls 164 of the filter modules 132, said aircurtain being directed from the respectively associated air curtainproducing arrangement 254 towards a narrow section 262 between the upperedges of the mutually opposed rows of modules 136 and this therebypreventing the stream of crude gas 120, which is loaded with fluid paintoverspray and is coming from the application area 108, from reaching theupper surface of the filter modules 132 and hence preventing the fluidpaint overspray from settling out of the stream of crude gas 120 ontothe upper surface of the filter modules 132.

The horizontal cross section of the flow chamber 128 through which thestream of crude gas is arranged to flow decreases suddenly in the narrowsection 262 of the flow chamber 128 so that the flow rate of the streamof crude gas is significantly higher in the lower section 263 of theflow chamber 128 located underneath the narrow section 262 than it is inthe upper section 260 of the flow chamber 128 located above the narrowsection 262.

The average direction of flow of the air in the transverse air curtainson the upper surface of the filter modules 132 which are produced by theair curtain producing devices 254 is illustrated in FIG. 3 by means ofthe arrows 264.

The greater part of the air being passed through the application area108 is thus re-circulated in an air re-circulating system whichcomprises the application area 108, the flow chamber 128, the filtermodules 132, the exhaust air pipes 248, the exhaust air duct 250, theexhaust air fan 252 as well as the supply line and the air chamber abovethe application area 108, this thereby preventing the air that is beingfed through the air re-circulating system from being constantly heatedby the influx of fresh air via the air curtain producing devices 254.

As an alternative or in addition thereto, the process of admitting freshair could also be effected at other points in the air re-circulatingsystem, for example, directly into the supply line.

Since the separation of the fluid paint overspray from the stream ofcrude gas 120 by means of the filter elements 172 is effected by meansof a dry process, i.e. it is not washed out with the aid of a cleaningfluid, the air being fed through the air re-circulating system is notmoistened during the process of separating out the fluid paint oversprayso that no devices whatsoever are required for dehumidifying the airbeing fed through the air re-circulating system.

Furthermore, devices for the separation of fluid paint overspray from awashing and cleaning fluid are also not necessary.

Thanks to the presence of the filter modules 132 and due to the factthat the horizontal cross section of the flow chamber 128 through whichthe stream of crude gas is arranged to flow is significantly smaller inthe lower section 263 of the flow chamber 128 lying below the narrowsection 262 than it is in the upper section 260 of the flow chamber 128(for example, in the lower section 263, it amounts to only approximately35% to approximately 50% of the horizontal cross-sectional area of theflow chamber 128 in the upper section 260 thereof), the flow rate of thestream of crude gas is continuously increased on its way from theapplication area 108 through the flow chamber 128 up to the inletopenings 212 of the filter modules 132 thereby resulting in the streamof crude gas having a rising speed profile.

This rising speed profile has the consequence that particles emergingfrom the filter modules 132 cannot reach the application area 108.

Hereby, the speed of the stream of crude gas within the application area108 and in the upper section 260 of the flow chamber 128 amounts to upto approximately 0.6 m/s for example, whereas in the lower section 263of the flow chamber for example it lies within a range of approximately0.6 m/s to approximately 3 m/s and rises up to a maximum value within arange of approximately 3 m/s to approximately 5 m/s in the inletopenings 212 of the filter modules 132.

Due to the fact that the filter elements 172 are housed entirely withinthe filter modules 132, it is possible for the filter elements 172 to beactivated by the application of the auxiliary material and for thefilter elements 172 to be cleansed at any time during the currentpainting process in the application area 108.

If the width of the paint booth 110, i.e. its extent in the transversedirection 112, changes, then equally large filter modules 132 are usednonetheless; the device 126 for removing fluid paint overspray is inthis case adapted by merely increasing the spacing of the two rows ofmodules 136 from each other and by widening the accessible gangway 146.

The speed profile of the stream of crude gas in the event of such awidening of the paint booth 110 thus changes only in the area up to theaccessible gangway 146; from there, i.e. when passing the inlet openings212 of the filter modules 132 in particular, the speed profile of thestream of crude gas is only dependent on the quantity of crude gaspassing through per unit of time, but not however, on the geometry ofthe flow chamber 128.

The spacing of the (accessible) covering walls 164 of the filter modules132 from the lower edge of the vehicle bodies 102 being conveyed throughthe paint booth 110 amounts to at least approximately 1.5 m for reasonsof maintenance.

The filter elements 172 are cleansed by blasts of compressed air atcertain time intervals when their loading with fluid paint overspray andauxiliary material has reached a given value.

This cleansing process can take place (in dependence on the increase inpressure loss at the filter elements 172) once to six times per 8-hourworking shift, i.e. approximately every 1 to 8 hours for example.

The requisite blasts of compressed air are produced by means of ablast-emitting unit 266 which is arranged on the base body 174 of thefilter elements 172 of each filter module 132, whereby theblast-emitting unit 266 is capable of delivering blasts of compressedair via a blast valve 267 to compressed air tubes or compressed airlances 269 which run within the respective base body 174 and lead fromthe blast-emitting unit 266 into the interior spaces of the filterelements 172 (FIG. 19).

The blast-emitting unit 266 comprises a compressed air tank which isabruptly emptied by the opening of the blast valve 267.

From the interiors of the filter elements 172, the blasts of compressedair pass through the porous filter surfaces into the filter elementaccommodating chamber 170, whereby the barrier layer of auxiliarymaterial and the fluid paint overspray deposited thereon which is formedon the filter surfaces is detached from the filter surfaces so thatthese filter surfaces revert to their cleansed original state.

The compressed air lances 269 are not seated closely on the filterelements 172 so that the compressed air flows laterally between therespective compressed air lance 269 and the filter element 172, if thefilter cake is not passable.

The blast-emitting unit 266 comprises a refilling valve 268 via whichcompressed air is suppliable from a compressed air supply line 270 tothe blast-emitting unit 266 for the purposes of filling up thecompressed air tank of the blast-emitting unit 266, said air supply linebeing fed by a compressor 272 (see FIG. 19).

The compressed air pipeline 196, which leads to the outlet nozzles 200of the fluidising arrangement 198, is also attached via a compressed airvalve 274 to this compressed air supply line 270.

Furthermore, the fluid base 184 of each auxiliary material reservoir 176is also attached via an air supply line 278 provided with a compressedair valve 276 to the compressed air supply line 270.

By opening the burst valve 268, the compressed air valve 274 or thecompressed air valve 276 in either alternating manner or at the sametime, a cleansing process for the filter elements 172, whirling-up ofthe auxiliary material in the auxiliary material reservoir 176 i.e.fluidisation of the auxiliary material in the auxiliary materialreservoir 176 by means of the fluid base 184 can thus be initiated.

A non-return valve 280, which is controllable by the control device 210in the control position, is arranged in the compressed air supply line270 between the abovementioned compressed air valves and the compressor272.

The control device 210 blocks the supply of compressed air from thecompressor 272 to the abovementioned compressed air consuming units of afilter module 132 or of all the filter modules 132 by closing thenon-return valve 280 if it determines that there is an inadequate flowof crude gas through the filter elements 172.

In order to determine whether there is an adequate flow of crude gasthrough the filter elements 172, provision may be made for the controldevice 210 to monitor the operative state of the exhaust air fan 252 forexample.

This process of monitoring the operative state of the exhaust air fan252 can be effected by means of a differential pressure gauge (PDIA) 282which measures the drop in pressure between the pressure side and thesuction side of the exhaust air fan 252 for example.

As an alternative or in addition thereto, the operative state of theexhaust air fan 252 can also be monitored by the control device 210 bymeans of a current monitoring instrument (ESA) 284 and/or by means of afrequency converter (SC) 286.

Furthermore, provision may be made for the lack of an adequate flow ofcrude gas through the filter elements 172 to be determined by means of avolumetric flow meter (FIA) 288 which measures the flow of gas throughthe exhaust air duct 250 or through one or more of the exhaust air pipes248.

Furthermore, it is possible to determine whether there is a lack of anadequate flow of crude gas through the filter elements 172 by measuringthe drop in pressure across the filter elements 172 in one filter module132 or in all of the filter modules 132 by means of a differentialpressure gauge (PDIA) 289 which measures the drop in pressure betweenthe interior space of the respective filter module 132 on the one handand the interior space of the base body 174 on the other.

If, due to the signals transmitted thereto by the differential pressuregauge 282, the current monitoring instrument 284, the frequencyconverter 286 and/or the volumetric flow meter 288, the control device210 determines that the flow of crude gas through the filter elements172 lies below a given threshold value, then the supply of compressedair to at least one of the filter modules 132 is blocked by the closureof the non-return valve 280.

It is in this way that auxiliary material is prevented from entering theflow path of the crude gas and, in particular, is prevented fromentering the flow chamber 128 through the inlet opening 212 of a filtermodule 132 and from said chamber reaching the application area 108 as aresult of a whirling up process effected by means of the fluidising unit198, or due to cleansing of the filter elements 172 or due to thefluidising of the auxiliary material stored in the auxiliary materialreservoir 176.

This blockage of the compressed air supply can be effected for all ofthe filter modules 132 together or separately for each of the individualfilter modules 132. In the latter case, the process of determining lackof an adequate flow of crude gas through the filter elements 172 iseffected separately for each of the filter modules 132, and either eachfilter module 132 is provided with its own compressor 272 or thecompressed air supply lines 270 to the individual filter modules 132 arearranged to be blocked or opened individually by means of non-returnvalves 280 which are controllable independently of one another.

In the case of the previously described device 126 for separating fluidpaint overspray, the auxiliary material is introduced into the stream ofcrude gas exclusively within the filter modules 132 by the process ofwhirling up the auxiliary material in the respective auxiliary materialreservoir 176.

In order to be able to supply fresh auxiliary material to the auxiliarymaterial reservoirs 176 that are rigidly mounted in their workingpositions within the filter modules 132, the device 126 for removingfluid paint overspray comprises an auxiliary material supply device 290which is schematically illustrated in FIG. 17 and which comprises astorage tank 292 that may be constructed in the form of a blowpot or asimple fluidisation tank.

Blowpots themselves are known from JP 02123025 A or JP 06278868 A forexample and until now they were used in coating plants for conveyingpowder coating to the application tanks located in the proximity of theatomizers. They are relatively small closable containers having anair-permeable base through which air is passed to the tank for thepurposes of fluidising the powder and transportation thereof.

Whilst a blowpot can be emptied by the pressure of the fluidising air, apowder dosing pump 293 such as the so-called DDF pump described in WO03/024612 A1 for example is otherwise connected to the outlet side ofthe fluidisation tank for the purposes of conveying the material (seeFIG. 1), or else use is made of some other form of dosing pump whichproduces a conveying action in accord with the dense-phase flowprinciple using alternating suction/pressure such as is known from EP 1427 536 B1, WO 2004/087331 A1 or the one depicted in FIG. 3 of DE 101 30173 A1 for example.

For the purposes of filling the storage tank 292, there is arrangedabove it a larger storage vessel (a packing drum or “big bag”) 294 forthe fresh auxiliary material from which, in the simplest case, thematerial can trickle into the storage tank (silo) 292 through an openingwhich is closable by a flap. However, in order to continuously refillthe storage tank 292 even during the process of conveying the materialand to avoid time delays in operation, a mechanical conveyer system 296such as a cellular rotary feeder or a conveyer worm for example, ispreferably arranged between the storage vessel 294 and the storage tank292. When employing such a conveyer system, it can also be advantageousto specify a desirable amount for each charge, in the case of a cellularrotary feeder, the previously determined amount by which each cell isfilled.

The storage tank 292 is connected to each of the auxiliary materialreservoirs 176 by a main line 300 which branches out into two branches298 a, 298 b from which stub lines 302 extend to a respective one of theauxiliary material reservoirs 176. Hereby, each of the branches 298 a,298 b of the main line 300 leads to the auxiliary material reservoirs176 of a respective row of modules 136.

The main line 300 preferably consists of flexible hoses.

Hoses having an internal diameter of up to approximately 14 mm and inparticular, from approximately 6 mm to approximately 12 mm can be usedfor this purpose.

The stub lines 302 can be tubular and are each provided with amechanical pinch valve 304, whereby, in each case, a second pinch valve306 is arranged, in the direction of flow of the auxiliary material,beyond the point where the respective stub line 302 branches off.

Further pinch valves 309 are arranged at the junction between the twobranches 298 a, 298 b and the main line 300 in order to enable these twobranches 298 a, 298 b to be opened or closed as required.

In operation of the auxiliary material feeding device 290, the main line300 and each one of the stub lines 302 are initially empty. If a certainauxiliary material reservoir 176 is to be charged with fresh auxiliarymaterial, the main line beyond the branching-point of the associatedstub line 302 is blocked by closing the respectively associated pinchvalve 306, the pertinent stub line 302 is opened by opening theassociated pinch valve 304 and the auxiliary material is subsequentlyconveyed from the storage tank 292 to the pertinent auxiliary materialreservoir 176.

Subsequently, the previously described transportation path to thepertinent auxiliary material reservoir 176 is emptied and flushed. Thishas the advantage that the size of the charge is always preciselydetermined and is capable of being metered, and in addition, thetransportation path cannot be blocked since a process of flushing itinto the charged auxiliary material reservoir 176 is always effected.

Each of the stub lines 302 opens out into one of the side walls 178 ofthe respectively associated auxiliary material reservoir 176,preferably, at a point near the upper edge of the auxiliary materialreservoir 176 so that as large a quantity of the auxiliary material aspossible can be supplied through the stub line 302.

That stub line 302 which leads to the last auxiliary material reservoir176 of a row of modules 136 does not require a pinch valve arrangementmerely because all of the pinch valves 306 and 309 arranged in the mainline 300 upstream of this auxiliary material reservoir 176 must beopened for the purposes of charging this last auxiliary materialreservoir 176.

Instead of the previously described pinch valve devices, mechanicalpinch distributors or other forms of powder distributors known from thestate of the art can also be provided at the junctions of the auxiliarymaterial line system.

In an alternative embodiment of an auxiliary material feeding device 290which is illustrated in FIG. 28, the amount to which the storage tank292 is filled is not determined by the quantity delivered by thecellular rotary feeder 296, but rather, it is determined from the weightof the auxiliary material present in the storage tank 292.

To this end, a base 307 of the storage tank 292, which may be in theform of a fluid base, rests on a balance 309 which is supported on afoundation by the feet 311.

The storage tank 292 is connected by a ring-like flexible compensator313 to the cellular rotary feeder 296 which is fillable with freshauxiliary material from a (not illustrated in FIG. 28) packing drum or“Big Bag” via a flap 315.

The compensator 313 is connected by suitable fixing means 317 to amounting flange of the cellular rotary feeder 296 on the one hand and toa mounting flange of the storage tank 292 on the other.

Due to the compensator 313, the storage tank 292 is mechanicallydecoupled from the cellular rotary feeder 296 so that the weight of thestorage tank 292 and of the auxiliary material contained thereinor—after suitable calibration—just the weight of the fresh auxiliarymaterial present in the storage tank 292 is measured precisely by meansof the balance 309.

The compensator 313 may be formed of a flexible plastic material forexample.

Other than was the case for the embodiment of an auxiliary materialfeeding device 290 that is illustrated in FIG. 17, the fresh auxiliarymaterial in the embodiment illustrated in FIG. 28 is not conveyed fromthe storage tank 292 to the main line 300 by means of a powder dosingpump 293, but rather, by subjecting the interior space of the storagetank 292 to compressed air from a source of compressed air 319 when anon-return valve 321 that is arranged in the main line 300 is opened.

In principle however, it is also possible to combine a storage tank 292incorporating a balance 309 with a powder dosing pump 293, andconveyance of the fresh auxiliary material by means of compressed airintroduced into the storage tank 292 may also be combined with a processof determining the amount by which the storage tank 292 is filled fromthe quantity delivered by the cellular rotary feeder 296.

In all other respects, the embodiment of an auxiliary material feedingdevice 290 that is illustrated in FIG. 28 corresponds in regard to theconstruction and functioning thereof with the embodiment of such anauxiliary material feeding device 290 that is illustrated in FIG. 17,and to this extent, reference is made to the previous descriptionthereof.

Furthermore, in order to enable the auxiliary material mixed withoverspray that has accumulated in an auxiliary material reservoir 176 tobe extracted and disposed of or re-processed before supplying freshauxiliary material thereto, the device 126 for separating fluid paintoverspray comprises an auxiliary material removal device 308 which isillustrated schematically in FIG. 18.

For its part, the auxiliary material removal device 308 comprises anextractor fan 310, a vacuum cleaner fan for example, which forces spentauxiliary material out of a main line 312 that branches out into twobranches 314 a, 314 b, and into a collection tank 316 which is arrangedbelow the extractor fan 310.

Each one of the branches 314 a, 314 b of the main line 312 leads to theauxiliary material reservoirs 176 of a row of modules 136 and isattached to each of the auxiliary material reservoirs 176 of thepertinent row of modules 136 via a respective stub line 318 which isclosable by means of a pinch valve 320.

At the end of each branch 314 a, 314 b of the main line 312, there is arespective ball tap 322 through which, when needed, air is suppliable tothe main line 312 in order to facilitate the suction of the auxiliarymaterial from the main line 312 to the suction fan 310.

The stub lines 318 open out into the interior space 186 of therespective auxiliary material reservoir 176 just above the fluid base184, preferably, in a corner area of the auxiliary material reservoir176 where two of the side walls 178 meet together.

It is particularly expedient for the efficient removal of the spentauxiliary material from an auxiliary material reservoir 176 and for thisremoval process to be effected as completely as possible, if the stubline 318 branches out into two suction lines each of which opens intothe interior space 186 of the auxiliary material reservoir 176 at adifferent corner area.

If a certain auxiliary material reservoir 176 is to be emptied of spentauxiliary material mixed with overspray, then, for this purpose, thepinch valve 320 of the respectively associated stub line 318 is openedand the material present in the auxiliary material reservoir 176 issucked out through the stub line 318 and the main line 312 by means ofthe suction fan 310 and passed to the collection tank 316.

The suction process is terminated by the closure of the respectivelyassociated pinch valve 320.

During the suction process, the fluid base 184 of the pertinentauxiliary material reservoir 176 is kept continually in operation, i.e.compressed air is passed through it during the whole of the suctionprocess in order to fluidise the material and enhance its fluidity.

Furthermore, the process of sucking out the used material from theauxiliary material reservoir 176 can be assisted by operating thefluidising arrangement 198 of the pertinent auxiliary material reservoir176 continuously or periodically (6×5 seconds per minute for example)during the suction process because the material is then decompacted andmoved towards the access openings of the stub line 318 by means of astream of compressed air, which is applied to the material requiringextraction from above, through the outlet nozzles 200 of the fluidisingarrangement 198.

In the event that the process of sucking out the spent auxiliarymaterial from one of the auxiliary material reservoirs 176 does notfunction in the proper manner, something which can be detected by thefact that the associated level sensor 204 is no longer indicating thatthe level is dropping, the operation of the device 126 for separatingfluid paint overspray does not have to be interrupted. Rathermore,auxiliary material from another of the auxiliary material reservoirs 176which is attached to the same branch 314 a or 314 b of the main line 312can be sucked out instead. Thereby, the blockade on the transportationof the material from the blocked auxiliary material reservoir 176 can,in many instances, be overcome so that the material can be sucked out ofthe previously blocked auxiliary material reservoir 176 at a later time.

The material containing auxiliary material as well as oversprayparticles which is sucked out of the auxiliary material reservoir 176can either be disposed of or at least be partly reused—if necessaryafter being reprocessed—in the coating plant.

Furthermore, provision may be made for the substances making up theauxiliary material to be selected in such a way that they can beexploited for purposes other than the coating of work pieces after theyhave been used in the coating plant. For example, the spent auxiliarymaterial can be used as a structural material or it may be thermallytreated and used, for example, in the brick industry or the cementindustry or the like, whereby the fluid paint overspray bonded to theauxiliary material can likewise be used as a source of energy in acombustion process necessary to the production process.

After the spent auxiliary material has been sucked out of an auxiliarymaterial reservoir 176, the latter is filled with fresh auxiliarymaterial by means of the auxiliary material feeding device 290 that hasalready been described hereinabove, namely, for example, up to a primaryfill-level of approximately 50% of the entire capacity of the auxiliarymaterial reservoir 176.

Due to the accumulation of wet paint overspray, which has a lowerdensity than that of the auxiliary material, in the mixture consistingof auxiliary material and overspray that is present in the auxiliarymaterial reservoir 176, the density of this mixture continuallydecreases during the operative state of a filter module 132 so that thebarrier layer building up on the filter elements 172 of the filtermodule 132 has an ever increasing volume.

In consequence, the level of the material in the auxiliary materialreservoir 176 decreases continually immediately before the process ofcleaning the filter elements 172.

At a given residual level which corresponds to approximately 10% of thecapacity of the auxiliary material reservoir 176 for example, theauxiliary material mixed with overspray is sucked out of the auxiliarymaterial reservoir 176 as has been previously described. Due to thissuction process prior to the process of cleaning the filter elements172, the effect is achieved that it is mainly the now unusable materialwhich has collected in the auxiliary material reservoir 176 and has notformed the barrier layer on the filter elements 172 that is removed fromthe auxiliary material reservoir 176.

As an alternative to this manner of procedure, provision may also bemade for the level of the material in the auxiliary material reservoir176 to be measured in each case after the process of cleaning the filterelements 172 of the filter module 132, and for a suction process to thenbe initiated if a given maximum level of e.g. 90% of the maximumcapacity of the auxiliary material reservoir 176 is reached.

In every case, the level of the material in the auxiliary materialreservoir 176 that triggers off a suction process is determined by meansof the level sensor 204 which is arranged in the respective auxiliarymaterial reservoir 176.

As an alternative or in addition to the time point for a suction processbeing determined by means of the level sensor 204 which is arranged inthe respective auxiliary material reservoir 176, the appropriate timepoint for initiating a suction process using the alternative embodimentof an auxiliary material reservoir 176 which is illustrated in FIG. 26and is provided with a container balance 223 can be determined asfollows:

-   material is whirled up from the auxiliary material reservoir 176;-   the effectiveness of the material contained in the auxiliary    material reservoir 176 is determined by a comparison of the weight    of the material contained in the auxiliary material reservoir 176    before the whirling-up phase and after the whirling-up phase; and-   material is removed from the auxiliary material reservoir 176 if the    effectiveness determined thereby falls below a given minimum value.

For this purpose for example, the material in the auxiliary materialreservoir 176 is whirled up by means of the fluidising device 198 of theauxiliary material reservoir 176 concerned during a whirling-up cycle inthe course of a plurality of successive whirling-up phases which arespaced from each other by whirling-up pauses, whereby the whirled-upmaterial is carried to the filter elements 172 of the filter moduleconcerned 132 and is deposited there at least to a partial extent.

During a whirling-up cycle for example, four whirling-up phases each ofe.g. 5 seconds duration may be effected, and between the whirling-upphases, there is a respective whirling-up pause of 10 seconds forexample.

The net whirling-up time of such a whirling-up cycle thus amounts to 4×5seconds=20 seconds for example.

Between successive whirling-up cycles, there is a longer whirling-uppause of approximately 60 seconds for example.

The weight of the material in the auxiliary material reservoir 176 asmeasured by the container balance 223 is stored before the whirling-upcycle and after the whirling-up cycle, and the amount of material thathas been carried away from the auxiliary material reservoir during thewhirling-up phases of the whirling-up cycle is determined by forming thedifference between these stored values.

The effectiveness is then determined by dividing the mass of thematerial that has been carried away from the auxiliary materialreservoir 176 during the whirling-up cycle by the net whirling-up timeof the whirling-up phases of the whirling-up cycle.

With an assumed mass loss of the material containing in the auxiliarymaterial reservoir 176 of 4 kg for example and a net whirling-up time of20 seconds, the effectiveness thus amounts to 12 kg/min for example.

The larger the thus determined effectiveness, the greater the amount ofmaterial that has been carried away from the auxiliary materialreservoir to the filter elements 172 and which has settled there as aprotective layer. The larger the effectiveness, the better the qualityof the material contained in the auxiliary material reservoir and inparticular, its ability to cling to the filter elements 172 and bind thefluid paint overspray.

Consequently, material is removed from the auxiliary material reservoirif the thus determined effectiveness falls below a—for exampleempirically determined—given minimum value.

The material removed by the suction process is replaced by freshauxiliary material which is supplied to the respective auxiliarymaterial reservoir 176 by means of the auxiliary material feeding device290.

A second embodiment of a plant 100 for painting vehicle bodies 102 whichis illustrated in FIG. 20 in the form of a schematic cross sectiondiffers from the previously described first embodiment in that separatetransverse air curtain guide plates 324, which serve to guide the airthat has been supplied by the air curtain production devices 254 towardsthe narrow section 262 between the upper section 260 and the lowersection 263 of the flow chamber 128, are arranged above the filtermodules 132.

These transverse air curtain guide plates 324 are inclined relative tothe respective neighbouring side wall 130 of the flow chamber 128 at anangle of e.g. approximately 1° to approximately 3° to the horizontal sothat liquids landing on the transverse air curtain guide plates 324 fromabove will not flow off into the narrow section 262, but rather, towardsthe side walls 130.

It is ensured in this way for example that paint leaking out from theapplication area 108 due to a burst hose or water originating from afire-extinguishing process will not enter the lower section 263 of theflow chamber 128 and from there, reach the filter modules 132, butrather it will be able to flow off to the sides of the flow chamber 128.

In this embodiment furthermore, the accessible gangway 146 between therows of modules 136 is subdivided into two halves 328 a, 328 b which areformed substantially mirror-symmetrically with respect to a verticallongitudinal centre plane 326 of the flow chamber 128 and are inclinedrelative to the longitudinal centre plane 326 at an angle of e.g.approximately 1° to e.g. approximately 3° to the respective horizontalsso that liquids landing on the accessible gangway 146 from above, suchas paint or water originating from a fire-extinguishing action forexample, will not spill over the lateral edges 330 of the accessiblegangway 146 into the inlet openings 212 of the filter modules 132, butrather, will be retained in the centre of the accessible gangway 146.

In addition, both the accessible gangway 146 and the transverse aircurtain guide plates 324 may be inclined to the horizontal in thelongitudinal direction 134 of the flow chamber 128 so that the liquidspresent on these elements can flow off into a drainage opening due tothe force of gravity.

As an alternative thereto, the gangway 146 may also comprise asubstantially horizontally oriented upper surface.

In all other respects, the second embodiment of a plant 100 for paintingvehicle bodies 102 that is illustrated in FIG. 20 corresponds in regardto the construction and functioning thereof with the first embodimentillustrated in FIGS. 1 to 19 so that to this extent, reference may bemade to the previous description.

As an alternative or in addition to the fluid base 184 illustrated inFIG. 13, the auxiliary material reservoirs 176 of the filter modules 132in the previously described plants 100 for painting vehicle bodies 102could also comprise other types of device 332 for mixing the materialpresent in the auxiliary material reservoir 176, for example, apneumatically operated agitating device 334 which is illustratedschematically in FIGS. 21 and 22.

The pneumatically operated agitating device 334 comprises an agitator336 having at least two agitator paddles 340 which are arranged inmutually non-rotational manner on a substantially vertically orientedagitator shaft 338 and an agitator turbine 342 which is illustrated in apurely schematic manner in FIGS. 21 and 22 and by means of which theagitator shaft 338 is settable into rotary motion about its verticalaxis.

The agitator paddles 340 are arranged on the agitator shaft 338 such asto be mutually displaced in the axial direction of the agitator shaft338 and to have an angular displacement of approximately 180° forexample.

Compressed air is suppliable to the agitator turbine 342 by way of acompressed air supply line 344.

When compressed air is supplied to the agitator turbine 342 via thecompressed air supply line 344, the compressed air being suppliedthereto sets the agitator turbine 342 into rotary motion about itsvertical axis, whereupon the agitator shaft 338 that is connected to theagitator turbine 342 in mutually non-rotational manner is likewise setin motion.

The material present in the auxiliary material reservoir 176 is therebymixed by the rotating agitator paddles 340 and the surface of thematerial located in the auxiliary material reservoir 176 is smoothed.Material bridges that have been formed in the auxiliary materialreservoir 176 by an undermining process are broken up.

In this way, thorough mixing of the material in the auxiliary materialreservoir 176 and evening-out of the level of the material within theauxiliary material reservoir 176 is obtained.

Due to the pneumatic drive for the agitating device 334, formation ofsparks within the auxiliary material reservoir 176 is prevented andadequate protection against the risk of explosion is ensured.

An alternative embodiment of a device 332 for mixing the materialpresent in the auxiliary material reservoir 176 that is illustrated inFIGS. 23 and 24 comprises an electric motor 346 which is arrangedlaterally beside the auxiliary material reservoir 176 whilst its driveshaft 348 is passed through a side wall 178 of the auxiliary materialreservoir 176 and is provided with a plurality of, four for example,paddles 350 which are fixed to the drive shaft 348 and are arrangedthereon such as to be mutually displaced in the axial direction of thedrive shaft 348 and to have a respective angular displacement ofapproximately 90° for example.

The paddles 350 are set into rotary motion about their substantiallyhorizontally oriented axes as a result of the rotation of the driveshaft 348 by means of the electric motor 346, whereby the paddles 350mix the material present in the auxiliary material reservoir 176 whilstsmoothing its surface and breaking up material bridges that havedeveloped in the auxiliary material reservoir 176.

The conversion of a currently existing device 126 for separating fluidpaint overspray from a stream of crude gas containing oversprayparticles can be effected in the following manner by using the filtermodules 132 of the previously described plants 100:

Firstly, part of the existing device is dismantled so that the spacethat is to be occupied by a filter module 132 in its working position isfreed up.

Subsequently, a filter module 132 is arranged in the working positionthat has been freed-up in this manner and it is connected to the supportstructure for the application area 108 and in particular, to the boothwalls 114 of the paint booth 110.

Subsequently, these steps are repeated until all of the filter modules132 have been arranged in their working position and connected to thesupport structure for the application area 108.

In this way for example, an existing device for separating fluid paintoverspray using a wet process can be replaced by the previouslydescribed, modularly constructed device 126 for separating fluid paintoverspray using a dry process without any need to dismantle theapplication area 108 of the plant 100 for painting vehicle bodies 102for this purpose.

In the case of the previously described devices 126 for separating fluidpaint overspray from a stream of crude gas 120 containing oversprayparticles, each filter module 132 has a separate auxiliary materialreservoir 176 associated therewith.

By contrast, in the case of the alternative embodiments of such a device126 for separating fluid paint overspray that are described below withreference to FIGS. 29 to 33, a plurality of filter modules 132 areassociated with the same reservoir 176 for auxiliary material whichaccommodates the material (auxiliary material and fluid paint overspray)that has been cleaned off the filter elements 172 of this plurality ofassociated filter modules 132.

In all other respects these embodiments of a device 126 for separatingfluid paint overspray from a stream of crude gas containing oversprayparticles that are illustrated in FIGS. 29 to 33 and the paint shop 100containing such a device 126 correspond in regard to the constructionand functioning thereof with the embodiments that were describedhereinabove with reference to FIGS. 1 to 28.

In order to enable the auxiliary material to be supplied to the streamof crude gas without the danger that the auxiliary material will enterthe application area 108 of the paint shop 100, and in order to enableauxiliary material cleaned off the filter elements 172 together withfluid paint overspray to be caught, each group of several e.g. threefilter modules 132 is associated in the embodiment of a device 126 forseparating fluid paint overspray from the stream of crude gas that isillustrated in FIGS. 29 to 31 with a common reservoir 176 which extendsin the longitudinal direction 134 of the device 126 over the entirelength of the e.g. three associated filter modules 132 (see FIG. 30).

The reservoir 176 is substantially in the form of a trough and comprisesan upper inlet section 478 as well as a mixing section 480 which adjoinsthe inlet section 478 at the lower end thereof.

The inlet section 478 is bounded by two end walls 482 which extendperpendicularly relative to the longitudinal direction 134 and twomutually opposite side walls 484 which extend from the one end wall 482up to the other end wall 482 and are inclined to the vertical at anangle of at least approximately 30°.

The mixing section 480 adjoining the lower end of the inlet section 478is substantially cylindrical and comprises an outer wall 486 which is inthe form of a section of a cylinder and extends over a peripheral angleof approximately 270° for example, the upper edges of the outer walladjoining the lower edges of the side walls 484 of the inlet section 478of the reservoir 176 so that the mixing section 480 opens out upwardlyinto the inlet section 478.

A fluidising device 198 which is held on one of the side walls 484 ofthe inlet section 478 of the reservoir 176 serves to deliver blasts ofcompressed air into the material accommodated in the reservoir 176 whichis located therebelow in order to whirl up this material and thusintroduce this material, including the auxiliary material containedtherein, into the stream of crude gas which is being passed through theinlet section 478 of the reservoir 176.

When the plant 100 is functioning, the fluidising means 198 is operatedintermittently, for example, four times per minute for approximately 5seconds on each occasion.

The fluidising means 198 comprises a plurality of, at least two perfilter module 132 for example, outlet nozzles 500 for the supply ofcompressed air, the nozzles being in the form of cone jets each of whichcan produce a cone of compressed air that widens out downwardly towardsthe mixing section 480 of the reservoir 176.

The outlet nozzles 500 are arranged in a compressed air pipeline 496which is passed through one of the side walls 484 of the inlet section478 of the reservoir 176 and leads to a source of compressed air 502located outside the reservoir 176.

In the mixing section 480 of the reservoir 176, there is arranged amixing device 504 for effecting the thorough mechanical mixing of thematerial which has been cleaned off the filter elements 172 of thedifferent filter modules 132 and which fills the mixing section 480 upto a level 506 (FIG. 29).

As can best be perceived from FIG. 30, the mixing device 504 comprises arotary shaft 508 which extends in parallel with the longitudinaldirection 134 of the device 126 and is mounted by means of bearings 510on the end walls 582 of the reservoir 176 such as to be rotatable abouta horizontal axis of rotation 512 running parallel to the longitudinaldirection 134.

One end of the rotary shaft 508 is passed in fluid-tight manner throughone of the end walls 482 of the reservoir 176 and is coupled to a rotarydrive means 514 (an electric drive motor for example) which is locatedoutside the reservoir 176.

The rotary shaft 508 of the mixing device 504 can extend over the entirelength of the paint booth 118 of approximately 20 m for example.

The volume of the material required to fill the mixing section 480 ofthe reservoir 176 can amount to at least 750 l for example.

Several mixing tools 516 which can be in the form of paddles 518 orploughshares for example are fixed onto the rotary shaft 508 such as torotate therewith.

The inner contour of the mixing section 580 of the reservoir 176 isadapted to the outer contour of the mixing tools 516 of the mixingdevice 504 in such a way that, in the course of a complete revolution ofthe rotary shaft 508 of the mixing device 504 about its axis of rotation512, the mixing tools 516 sweep over a mixing region 520 having an outercontour which corresponds substantially to the inner contour of themixing section 480 of the reservoir 176.

Preferably, the mixing device 504 sweeps over substantially the entiretyof the mixing section 480 of the reservoir 176 whilst completing a fullrevolution about its axis of rotation 512.

Due to the mixing movement of the mixing device 504 as it is driven bymeans of the rotary drive means 514, the binding forces between theparticles of which the material in the reservoir 176 consists isdestroyed and mixing of the material in the longitudinal direction ofthe rotary shaft 508 is effected. Due to the mixing movement, there areno differences in concentration within the reservoir 176 and inparticular, the proportion of fresh auxiliary material on the one handto that of the auxiliary material cleaned off the filter elements 172and fluid paint overspray on the other is substantially equally greateverywhere in the reservoir 176.

In order to enable fresh auxiliary material to be supplied to thereservoir 176, an inlet 522 for fresh auxiliary material, which isconnected to a (not illustrated) source of fresh auxiliary material, isprovided in one end wall 482 of the reservoir 176.

In the end wall 482 facing the inlet 522 for fresh auxiliary material,there is provided a material outlet 524 which is arranged in the lowerregion of the mixing section 480 close to the lower peak of thecylindrical mixing section 480.

Auxiliary material that has been enriched with fluid paint overspray canbe extracted from the reservoir 176 through this material outlet 524 inorder to maintain the filling level 506 of the reservoir 176substantially constant despite the supply of fresh auxiliary materialthrough the inlet 522.

A mixing tool 516′ which assists in the process of discharging thematerial through the material outlet 524 is arranged on the rotary shaft508 near the material outlet 524, said mixing tool 516′ protruding fromthe rotary shaft 508 in the radial direction or towards an end wall inthe axial direction.

Instead of having just one paddle 518 protruding from the rotary shaft508 in the radial direction, the mixing tools 516 of the mixing device504 could also be in the form of a helix 526 which is coaxial with theaxis of rotation 512 of the mixing device 504.

In particular, the mixing device 504 may be provided with two helices526, 526′ which have mutually opposed directions of rotation.

Hereby, these helices may have the same pitch but different radii.

Due to the opposite directions of rotation of the two helices 526, 526′,particularly thorough mixing of the material located in the mixingsection 480 is achieved.

Furthermore, due to the action of the mixing device 504, the surface ofthe material contained in the reservoir 176 is smoothed, and materialbridges that may be formed in the reservoir 176 as a result of anundermining process are broken up.

Each filter module 132 is provided with a slot-like inlet opening 212which is in the form of an inlet channel 214 and has a through-flowcross section narrowing in the direction of flow of the partial streamof crude gas 528 up to a narrow section 240.

Hereby, the stream of crude gas entering the filter modules 132 from theflow chamber 128 is subdivided into respective partial streams of crudegas 528 that are associated with a respective filter module 132, thesepartial streams of crude gas 528 being deliberately diverted into theinlet section 178 of a respective reservoir 176 whereas direct access ofthe stream of crude gas from the flow chamber 182 to the filter elements172 is prevented.

The filter elements 172 of the filter modules 132 are cleaned at certaintime intervals by bursts of compressed air when the loading thereof withfluid paint overspray and auxiliary material has reached a given level.

This cleaning process may take place (in dependence on the increase inpressure loss across the filter elements 172) once to six times per8-hour working shift, i.e. approximately every 1-8 hours for example.

In the device 126 for separating fluid paint overspray describedhereinabove, the auxiliary material is supplied to the partial streamsof crude gas 528 exclusively by the process of whirling up the auxiliarymaterial in the respectively associated reservoir 176.

In order to be able to extract the auxiliary material mixed withoverspray that has collected in the reservoir 176 and pass it on fordisposal or reprocessing, the device 126 for separating fluid paintoverspray comprises a (not illustrated) auxiliary material removaldevice which is attached to the material outlets 524 of the reservoir176 and, for example, comprises a suction fan for sucking the materialout from the reservoirs 176.

The material containing auxiliary material with overspray particles thathas been removed from the reservoirs 176 may either be disposed ofor—possibly after reprocessing—at least partly reused in the coatingplant.

A second embodiment of a device 126 for separating fluid paint overspraythat is illustrated in FIG. 32 in the form of a schematic side view of amodule row 136, differs from the device 126 described hereinbefore inthat not all of the filter modules 132 of a module row 136 that arearranged one behind the other in the longitudinal direction 134 of thedevice 126 are associated with just one reservoir 176 which extends overthe entire length of the module row 136. Instead, each module row 136 issubdivided into a plurality of e.g. two groups of modules 566 a, 566 bwhich each comprise a plurality of e.g. four filter modules 132. Eachgroup of modules 566 a, 566 b is associated with a respective reservoir176 a and 176 b which accommodates the material (auxiliary material andfluid paint overspray) that has been cleaned off the filter elements 172of the filter modules 132 of the respective group of modules of 566 a,566 b.

Thus, in this embodiment of the device 126 for separating fluid paintoverspray, at least two reservoirs 176 a, 176 b are arrangedsuccessively in the longitudinal direction 134, whereby however, eachreservoir 176 a, 176 b still receives the material cleansed from aplurality of filter modules 132.

Furthermore, each of the reservoirs 176 a, 176 b comprises a mixingdevice 504 by means of which the material originating from differentfilter modules 132 and caught by the respective reservoir 176 a, 176 bis mixable.

In this embodiment, the end walls 482 of the reservoirs 176 a, 176 b arenot continuous in the vertical direction, but rather, comprise an upperinclined end wall section 568 which borders the inlet section 478 at thefront side and is inclined to the vertical in such a manner that theinclined end wall section 568 projects beyond the mixing section 480 ofthe relevant reservoir 176 a, 176 b in the longitudinal direction 134.

In consequence, sufficient space for accommodating a rotary drive means514 for each mixing device 504 can be created below the inclined endwall sections 568 of the reservoirs 176 a, 176 b that follow each otherin the longitudinal direction 134 and between the end walls of themixing sections 480 of this reservoir 176 a, 176 b.

Furthermore, care should be taken to ensure that sufficient space ismade available between the exhaust air pipes 248 and the storage tanks176 a, 176 b for installing the rotary shaft 508 of each mixing device504.

The groups of modules 566 a, 566 b which are arranged one behind theother in the longitudinal direction 134 of the device 126 may beassociated with different paint booths or with differing paintingsections within the same paint booth, for example a painting section forthe interior paintwork of the vehicle bodies 102 on the one hand and apainting section for the external finish of the vehicle bodies 102 onthe other.

As an alternative thereto, provision could also be made for differenttypes of paint to be applied to the vehicle bodies 102 in the differentpainting sections with which the groups of modules 566 a, 566 b areassociated, for example a primer on the one hand and a clear lacquer onthe other.

Paint is not applied to the vehicle bodies 102 in that area of the paintshop located above the area between the groups of modules 566 a, 566 b.

In all other respects, the embodiment of a device 126 for separatingfluid paint overspray which is illustrated in FIG. 32 corresponds inregard to the construction and functioning thereof with the embodimentillustrated in FIGS. 29 to 31 and so to this extent reference is made tothe preceding description.

An embodiment of a device 126 for separating fluid paint overspray whichis illustrated in FIG. 33 in the form of a schematic side view of amodule row 136 differs from the embodiment illustrated in FIGS. 29 to 31in that the number of filter modules 132 associated with the samereservoir 176 is larger (eight filter modules 132 for example). Inconsequence, the extent of the reservoir 176 in the longitudinaldirection 134 of the device 126 is very large (being 16 m or more forexample).

In the case of a reservoir 176 of such great length, a very high poweredrotary drive means 514 would have to be used in order to set in motion arotary shaft 508 which is provided with mixing tools 516 and extendsover the entire length of the reservoir 176.

Consequently, in the case of the embodiment illustrated in FIG. 33,provision is made for the mixing device 504 to comprise two rotaryshafts 508 a, 508 b which succeed one another in the longitudinaldirection 134 and in the direction of the common axis of rotation 512and each of which is driven by its own rotary drive means 514 a, 514 b,said drive means being respectively mounted in rotatable manner on thefront end wall 482 a and on the rear end wall 482 b of the reservoir 176as well as in a bearing 572 in the centre of the reservoir 176.

Each of the rotary shafts 508 a, 508 b is provided with one or moremixing tools 516, with helices 526 for example, for mixing the materialaccommodated in the reservoir 176.

Due to the mixing tools 516 being shared between two mutually separatelymounted and independently driven rotary shafts 508 a, 508 b, the drivingpower of the rotary drive means 514 a, 514 b which is required forproducing the rotary motion of the mixing tools 516 can be reduced.

In this embodiment too, the end walls 482 a, 482 b of the reservoir 176are not continuous in the vertical direction, but rather comprise anupper inclined end wall section 568 which borders the inlet section 478at the front side and is inclined to the vertical in such a manner thatthe inclined end wall section 568 projects beyond the mixing section 480of the reservoir 176 in the longitudinal direction 134.

In consequence, sufficient space for accommodating a respective rotarydrive means 514 a, 514 b for the mixing device 504 can be created belowthe inclined end wall sections 568.

In all other respects, the embodiment of a device 126 for separatingfluid paint overspray which is illustrated in FIG. 33 corresponds inregard to the construction and functioning thereof with the embodimentillustrated in FIGS. 29 to 32, and so to this extent reference is madeto the preceding description.

A further embodiment of a paint shop 100 that is illustrated in FIGS. 34and 35, differs from the embodiments of such a plant describedhereinabove in regard to the construction of the painting devices and inparticular, of the application units in these painting devices. Thespecial construction of these painting devices and of the applicationarea of the paint shop 100 described below may be combined with each ofthe embodiments and manner of functioning of a device 126 for separatingfluid paint overspray from the stream of crude gas containing oversprayparticles that have been described hereinabove.

The basic construction of the further embodiment of a paint shop 100illustrated in FIGS. 34 and 35 is known from DE 10 2005 048 579 A1 forexample, so that to this extent, reference is made thereto and thecontents thereof are incorporated in this description.

The paint shop 100 illustrated in FIG. 34 in the form of a cross sectioncomprises a paint booth 602 having an application area 604, a (notillustrated) plenum arranged above the paint booth 602 through which airis supplied to the paint booth 602, and a filter room 606 which isarranged underneath the paint booth 602 and wherein air that has beensubjected to paint overspray in the paint booth 602 is cleaned.

Vehicle bodies are conveyable through the application area 604 in thepaint booth 602 by means of a (not illustrated) conveyor device.

For the purposes of painting the vehicle bodies within the applicationarea 604 of the paint booth 602, a painting device 608 is arranged inthe paint booth 602.

The painting device 608 comprises a painting robot 612 which, forexample, is arranged on a side wall 610 of the paint booth 602 andcarries an application unit 614 in the form of a paint applicator forapplying paint to the vehicle bodies.

The application unit 614 is arranged on a moveable end of the paintingrobot 612. An outlet opening 616 of the application unit 614 (see FIG.35) can thus be directed toward a plurality of surfaces of the vehiclebodies in order to enable the vehicle bodies to be painted in aparticularly simple manner.

The painting device 608 has a first supply line 618 for supplying afirst paint from a first paint tank 620 to the application unit 614 bymeans of a first pump 622 arranged in the first supply line 618 and asecond supply line 624 for supplying a second paint from a second painttank 626 to the application unit 614 by means of a second pump 628 thatis arranged in the second supply line 624.

A choice can thus be made between two different paints for painting thevehicle bodies by means of the painting device 608.

Furthermore, the outlet opening 616 of the application unit 614 can bedirected toward a plurality of surfaces of the paint shop 100, which arenot to be painted, by means of the painting robot 612 in order toprovide them with a protective layer.

To this end, the painting device 608 has a third supply line 630 forsupplying a medium from a medium tank 632 to the application unit 614,wherein a third pump 634 is provided in the third supply line 630 inorder to supply the medium from the medium tank 632 by way of the thirdsupply line 630 to the application unit 614.

The application unit 614 thus also serves as a medium delivery device.

The medium contained in the medium tank 632 is a medium which differsfrom the paint used for painting the vehicle bodies. In particular, themedium is a layer-forming medium.

A layer-forming medium for example is a precoat material or an auxiliarymaterial which comprises, in particular, chalk, stone dust, aluminiumsilicate, aluminium oxide, silicon oxide, powder coating and/or thelike. Furthermore, the layer-forming medium may comprise a substancewhich has chemically reactive groups such as amine groups for example.

The layer-forming medium is applicable by means of the application unit614, in particular, to those surfaces of the paint shop 100 which aresubjected to paint overspray when the paint shop 100 is performing apainting operation.

Such surfaces of the paint shop 100 are, in particular, the inner faces636 of the side walls 610 of the paint booth 602, the upper surfaces 638of the filter devices 640 arranged in the filter room 606 and a (notillustrated) grating base that is arranged between the paint booth 602and the filter room 606.

Due to the application of the layer-forming medium onto surfaces thatare subjected to paint overspray when the paint shop 100 is performing apainting operation, the paint overspray does not adhere directly to thesurfaces of the paint shop 100, but rather, to a protective layer formedby means of the medium or it reacts chemically therewith so that asimple process for cleansing paint overspray from the surfaces of thepaint shop 100 is ensured.

It is thereby possible in particular, to provide a process for cleaningthe surfaces of the paint shop 100 that are contaminated with paintoverspray wherein the contaminated surfaces of the paint shop 100 aresubjected to a cleaning medium by means of the application unit 614.

After a cleaning process and especially when using an aqueous cleaningmedium, the cleansed surfaces of the paint shop 100 are subjectable to adrying medium by means of the application unit 614.

For the purposes of switching between a paint delivery mode and a mediumdelivery mode of the painting device 608, there is provided a switchingdevice 642 which is arranged on the application unit 614 for example(see FIG. 35).

A fluid connection between the first supply line 618 and a delivery line644 that opens out into the outlet opening 616 of the application unit614, between the second supply line 624 and the delivery line 644, or,between the third supply line 630 and the delivery line 644 isselectively producible by means of the switching device 642.

In order to prevent paint being applied to a surface which is not to bepainted, or to prevent a vehicle body which is to be painted from havingan e.g. layer-forming medium applied thereto, the painting device 608comprises a reservoir 646 which is suppliable with any paint that isstill disposed in the delivery line 644 when switching from a paintdelivery mode into another paint delivery mode or into a medium deliverymode and/or with the medium that is still disposed in the delivery line644 when switching from a medium delivery mode into a paint deliverymode or into another medium delivery mode.

In order to enable the application unit 614 to be supplied with mutuallydiffering media, one could, on the one hand, arrange for the medium tank632 to be replaceable.

On the other hand, one could provide further (not illustrated) supplylines which lead from further (not illustrated) medium containers to theswitching device 642 so that a selection can be made there not justbetween different paints from the first paint tank 620 and the secondpaint tank 626 and a medium from the medium tank 632 but additionally,from a plurality of medium tanks containing different media.

The paint shop 100 described hereinabove functions as follows:

Before introducing a vehicle body by means of the conveyor device intothe application area 604 of the paint booth 602 of the paint shop 100, aprotective layer is applied to the surfaces of the paint shop 100 thatwill be subjected to paint overspray when a painting operation isoccurring in the paint shop 100.

To this end, the outlet opening 616 of the application unit 614 of thepainting device 608 is directed towards a surface such as the innersurfaces 636 of the side walls 610 of the paint booth 602 for example,onto which a layer-forming medium is to be applied.

The switching device 642 is switched into a medium delivery mode inwhich the third supply line 630 is in fluid connection with the deliveryline 644 of the application unit 614 so as to supply a layer-formingmedium from the medium tank 632 to the outlet opening 616 of theapplication unit 614 and thus to the inner surfaces 636 of the sidewalls 610 of the paint booth 602.

The medium is sucked in from the medium tank 632 and supplied by way ofthe third supply line 630 to the switching device 642 of the applicationunit 614 by means of the third pump 634.

Subsequently, further surfaces which are to be protected such as theupper surfaces 638 of the filter devices 640 or the (not illustrated)grating base of the paint booth 602 for example, have the layer-formingmedium applied thereto so that a protective layer is formed on surfacesthat may be subjected to paint overspray when a painting operation isoccurring in the paint shop 100.

After these method steps have been concluded, the fluid connectionbetween the third supply line 630 and the delivery line 644 isinterrupted by means of the switching device 642 and, for example, afluid connection is established between the first supply line 618 andthe delivery line 644.

In order to supply the medium that is still present in the delivery line644 to the reservoir 646, the outlet opening 616 is directed towards aninterior space of the reservoir 646 and paint is supplied from the firstpaint tank 620 to the application unit 614 by means of the first pump622 until such time as the delivery line 644 no longer contains anymedium.

As an alternative or in addition thereto, provision may be made for thedelivery line 644 to be rinsed with a detergent between the processes ofdelivering medium and delivering paint.

A vehicle body being conveyed to the paint booth 602 by means of theconveyor device is then painted in known manner by means of theapplication unit 614 of the painting device 608 which is arranged on thepainting robot 612.

Hereby, the paint emerging from the outlet opening 616 is not applied inits entirety to the vehicle body being painted. Rathermore, paintoverspray is formed and this falls down onto surfaces of the paint shop100 that are not to be painted.

Due to the protective layer that has been previously applied to thesesurfaces by means of the application unit 614 of the painting device608, the paint overspray does not adhere directly to the surfaces of thepaint shop 100, but rather, to the protective layer that has been formedby means of the layer-forming medium or else it reacts chemicallytherewith.

After one or more painting processes and the removal from the paintbooth 602 of the last vehicle body to have been painted in the paintbooth 602, there follows a simple cleaning of the surfaces of the paintshop 100 that have been subjected to paint overspray whereby theprotective layer formed by means of the layer-forming medium togetherwith the paint overspray adhering thereto is removed from the surfacesof the paint shop 100.

This can be effected by a manual cleaning process for example.

As an alternative or in addition thereto, an automatic cleaning processcan be effected by means of the application unit 614 of the paintingdevice 608. To this end, the medium tank 632, which contains thelayer-forming material, is replaced by another medium tank 632 whichcontains an aqueous cleaning medium for example.

After a change-over process has occurred at the switching device 642 forthe purposes of establishing a fluid connection between the third supplyline 630 and the delivery line 644, the surfaces of the paint shop 100to which the layer-forming medium was previously applied are nowsubjected to the cleaning medium, whereby the protective layer that wasformed by means of the layer-forming medium and has now absorbed thepaint overspray is removed from the surfaces of the paint shop 100.

Thereafter, the material of the protective layer contaminated with paintoverspray is removed from the paint shop 100 either manually or by meansof (not illustrated) conveyor belts.

After the cleaning process, the medium tank 632 containing the cleaningmedium is replaced by a medium tank 632 containing a drying medium suchas a gaseous medium for example, and the cleansed surfaces of the paintshop 100 are subjected to the drying medium by means of the applicationunit 614.

As soon as the cleansed surfaces of the paint shop 100 are dry, themedium tank 632 containing the drying medium is replaced by the mediumtank 632 which contains the layer-forming medium.

The paint shop 100 is in this way returned to its starting state so thata further coating process can be started in preparation for the paintingoperation of the paint shop 100.

Due to the fact that a stream of a medium forming a layer differing froma paint that is used for painting the workpieces is deliverable by meansof the application unit for the purposes of applying a layer to asurface, the painting device is employable in a flexible andspace-saving manner and comprises just a small number of components.

All the individual features of the different embodiments of paint shops100 that have been described hereinabove may be freely and arbitrarilycombined with the individual features of the other embodimentsdescribed, namely, both in regard to their construction as well as inregard to their use and manner of operation.

The invention claimed is:
 1. A paint shop, comprising at least onepainting device incorporating at least one application unit for paintingworkpieces with a fluid paint and a device for separating fluid paintoverspray from a stream of crude gas, wherein the device for separatingfluid paint overspray from a stream of crude gas comprises at least onefilter device for separating fluid paint overspray from a stream ofcrude gas which incorporates at least one filter element for separatingthe overspray from the stream of crude gas and at least one auxiliarymaterial reservoir for accommodating an auxiliary material which issupplied to the stream of crude gas loaded with fluid paint overspray,wherein the auxiliary material reservoir is provided with a balance,wherein an effectiveness of the material contained in the auxiliarymaterial reservoir is determined by a comparison of the weight or themass of the material contained in the auxiliary material reservoir priorto a whirling-up phase, wherein material is whirled up from theauxiliary material reservoir, with the weight or the mass of thematerial contained in the auxiliary material reservoir after thewhirling-up phase, and wherein the device for separating fluid paintoverspray from a stream of crude gas comprises an auxiliary materialfeeding device for supplying fresh auxiliary material to the auxiliarymaterial reservoir, the auxiliary material feeding device comprising astorage tank for storing fresh auxiliary material and a supply lineopening out into the auxiliary material reservoir for conveying freshauxiliary material from the storage tank to the auxiliary materialreservoir.
 2. A paint shop in accordance with claim 1, wherein thefilter device comprises at least one inlet opening through which thestream of crude gas enters the filter device, wherein the inlet openingis configured and oriented in such a manner that the stream of crude gasenters the filter device such that it is directed into the auxiliarymaterial reservoir in such a way that it is diverted in an interiorspace of the auxiliary material reservoir.
 3. A paint shop in accordancewith claim 1, wherein the device for separating fluid paint oversprayfrom a stream of crude gas comprises an auxiliary material removaldevice for removing material from the auxiliary material reservoir ifthe determined effectiveness falls below a minimum value.
 4. Anauxiliary material reservoir for accommodating an auxiliary materialwhich is supplied to a stream of crude gas that is loaded with fluidpaint overspray before the stream of crude gas has passed at least onefilter element for separating the overspray from the stream of crudegas, wherein the auxiliary material reservoir is provided with abalance, wherein an effectiveness of the material contained in theauxiliary material reservoir is determined by a comparison of the weightor the mass of the material contained in the auxiliary materialreservoir prior to a whirling-up phase, wherein material is whirled upfrom the auxiliary material reservoir, with the weight or the mass ofthe material contained in the auxiliary material reservoir after thewhirling-up phase, and wherein the auxiliary material reservoir isconnected to an auxiliary material feeding device for supplying freshauxiliary material to the auxiliary material reservoir, the auxiliarymaterial feeding device comprising a storage tank for storing freshauxiliary material and a supply line opening out into the auxiliarymaterial reservoir for conveying fresh auxiliary material from thestorage tank to the auxiliary material reservoir.
 5. An auxiliarymaterial reservoir in accordance with claim 4, wherein the auxiliarymaterial reservoir is provided with an agitator.
 6. An auxiliarymaterial reservoir in accordance with claim 4, wherein the auxiliarymaterial reservoir comprises a lower section which is mechanicallydecoupled from an upper section of the auxiliary material reservoir. 7.An auxiliary material reservoir in accordance with claim 6, wherein theweight of the lower section of the auxiliary material reservoir and ofthe material contained therein is determinable by means of the balance.8. An auxiliary material reservoir in accordance with claim 4, whereinthe auxiliary material reservoir is connected to an auxiliary materialremoval device for removing material from the auxiliary materialreservoir if the determined effectiveness falls below a minimum value.9. A method for the operation of a paint shop, comprising the followingprocessing steps: applying fluid paint to workpieces that are to bepainted, by means of at least one application unit of at least onepainting device; introducing a stream of crude gas containing oversprayparticles into a filter device; and separating the overspray from thestream of crude gas by means of at least one filter element arranged inthe filter device; wherein an auxiliary material is supplied to thestream of crude gas loaded with fluid paint overspray, wherein a mixtureof auxiliary material and fluid paint overspray is arranged in anauxiliary material reservoir and the weight or the mass of the mixturein the auxiliary material reservoir is determined by means of a balance,wherein material is whirled up from the auxiliary material reservoir andthe effectiveness of the material contained in the auxiliary materialreservoir is determined by a comparison of the weight or the mass of thematerial contained in the auxiliary material reservoir prior to thewhirling-up phase with the weight or the mass of the material containedin the auxiliary material reservoir after the whirling-up phase, andwherein fresh auxiliary material is supplied to the auxiliary materialreservoir by an auxiliary material feeding device comprising a storagetank for storing fresh auxiliary material and a supply line opening outinto the auxiliary material reservoir for conveying fresh auxiliarymaterial from the storage tank to the auxiliary material reservoir. 10.A method in accordance with claim 9, wherein the stream of crude gas isintroduced into the filter device through at least one inlet opening insuch a way that the stream of crude gas enters the filter device such asto be directed into the auxiliary material reservoir for accommodatingthe auxiliary material, wherein the stream of crude gas is diverted inan interior space of the auxiliary material reservoir.
 11. A method inaccordance with claim 9, wherein material is extracted from theauxiliary material reservoir when a difference of the weight or mass ofthe material contained in the auxiliary material reservoir prior to thewhirling-up phase and after the whirling-up phase falls below a givenminimum value.
 12. A method in accordance with claim 9, wherein theweight or the mass of material in an auxiliary material reservoir ismeasured by means of a balance prior to and after a whirling-up cycleduring which a plurality of whirling-up phases are carried out, and theamount of material that has been withdrawn from the auxiliary materialreservoir is determined by formulating the difference.
 13. A method inaccordance with claim 9, wherein the effectiveness of the materialcontained in the auxiliary material reservoir is determined by acomparison of the weight or the mass of the material contained in theauxiliary material reservoir prior to a whirling-up cycle during which aplurality of whirling-up phases are carried out with the weight or themass of the material contained in the auxiliary material reservoir afterthe whirling-up cycle.
 14. A method in accordance with claim 9, whereinthe workpieces that are to be painted are vehicle bodies.
 15. A methodin accordance with claim 9, wherein material is removed from theauxiliary material reservoir if the determined effectiveness falls belowa minimum value.